Gus Woltmann » Space & Time

Space Telescopes

admin — Fri, 25 Sep 2009 13:20:40 +0000

Space observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects.
A large number of observatories have been launched into orbit, and most of them have greatly enhanced our knowledge of the cosmos.
Performing astronomy from the Earth’s surface is limited by the filtering and distortion of electromagnetic radiation due to the Earth’s atmosphere.
This makes it desirable to place astrononomical observation devices into space.
As a telescope orbits the Earth outside the atmosphere it is subject neither to twinkling (distortion due to thermal turbulences of the air) nor to light pollution from artificial light sources on the Earth.
But space-based astronomy is even more important for frequency ranges which are outside of the optic window and the radio window, the only two wavelength ranges of the electromagnetic spectrum that are not severely attenuated by the atmosphere.
For example, X-ray astronomy is nearly impossible when done from the Earth, and has reached its current important stand within astronomy only due to orbiting satellites with X-ray telescopes such as the Chandra observatory or XMM-Newton observatory.
Infrared and ultraviolet are also greatly blocked..
Active optics
Active optics is a relatively new technology for reflecting telescopes developed in the 1980s, which has more recently enabled the construction of a generation of telescopes with 8 metre primary mirrors.
Active optics works by “actively” adjusting the telescope’s mirrors.
This method is used by, among others, the Nordic Optical Telescope, the New Technology Telescope and the Keck telescopes, as well as all large telescopes built in the last decade.
Most modern telescopes are reflectors, with the primary element being a very large mirror.
Historically, the mirrors had to be very thick to hold its shape to the required accuracy as the telescope travelled across the sky.
A new generation of telescopes built since the 1980s uses instead very thin mirrors, which are too thin to keep themselves rigidly in the correct shape.
Instead, an array of actuators behind the mirror keeps it in an optimal shape.
The telescope may also be segmented into many small mirrors, preventing most of the gravitational distortion that occurs in large, thick mirrors..
European Southern Observatory
The European Southern Observatory (ESO, also more formally the European Organisation for Astronomical Research in the Southern Hemisphere) is an intergovernmental research organisation for astronomy, composed and supported by eleven countries from the European Union plus Switzerland.
Created in 1962, it is famous for building and operating some of the largest and most technologically advanced telescopes in the world, such as the New Technology Telescope (NTT), which was one of the telescopes which pioneered active optics technology, and more recently the VLT (Very Large Telescope), consisting of four 8-meter class telescopes.
In 2005, it obtained the first picture of an exosolar planet, 2M1207b, orbiting a brown dwarf 260 light-years away..
Telescope
A telescope is an instrument designed for the observation of remote objects.
The term usually refers to optical telescopes, but there are telescopes for most of the spectrum of electromagnetic radiation and for other signal types. An optical telescope gathers and focuses visible light and other electromagnetic radiation.
Telescopes increase the apparent angular size of distant objects, as well as their apparent brightness.
Telescopes work by employing one or more curved optical elements – lenses or mirrors – to gather light or other electromagnetic radiation and bring that light or radiation to a focus, where the image can be observed, photographed or studied.
Optical telescopes are used for astronomy and in many non-astronomical instruments including theodolites, transits, spotting scopes, monoculars, binoculars, camera lenses and spyglasses..

“This article is brought to you by Gus Woltmann”.

Space Station

admin — Fri, 25 Sep 2009 13:18:45 +0000

International Space Station
The International Space Station (ISS) is a joint project of five space agencies.
The ISS has seen the first space tourist, Dennis Tito, who spent 20 million USD to fly aboard a Russian supply mission and the first space wedding when Yuri Malenchenko on the station married Ekaterina Dmitriev who was in Texas..
Mir
Mir was a highly successful Soviet (and later Russian) orbital station.
It was humanity’s first consistently inhabited long-term research station in space.
Through a number of collaborations, it was made internationally accessible to cosmonauts and astronauts of many different countries.
Mir was assembled in orbit by successively connecting several modules, each launched separately from February 19, 1986 to 1996.
The station existed until March 23, 2001, at which point it was deliberately de-orbited, and broke apart during atmospheric re-entry..
Space debris
Space debris or orbital debris, also called space junk and space waste, are the objects in orbit around Earth created by man that no longer serve any useful purpose.
They consist of everything from entire spent rocket stages and defunct satellites to explosion fragments, paint flakes, dust and slag from solid rocket motors, coolant released by RORSAT nuclear powered satellites, and other small particles..
Space Shuttle Columbia
Space Shuttle Columbia (NASA Orbiter Vehicle Designation: OV-102) was the first space shuttle in NASA’s orbital fleet.
Its first mission, STS-1, lasted from April 12 to April 14, 1981.
On February 1, 2003, Columbia disintegrated during re-entry on its 28th mission; all seven crew members aboard were killed..

“This article is brought to you by Gus Woltmann”.

Space Probes

admin — Fri, 25 Sep 2009 13:15:44 +0000

Exploration of Mars
The exploration of Mars has been an important part of the space exploration missions of the Soviet Union (later Russia), the United States, Europe, and Japan.
Dozens of unmanned spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s.
These missions were aimed at gathering data and answering questions about the red planet and its past that may yield further insight into Earth’s past, present, and future..
Voyager program
The Voyager program consisted of a pair of unmanned scientific probes, Voyager 1 and Voyager 2, launched in 1977.
They were sent to study Jupiter and Saturn, using an advantageous planetary alignment of the late 1970s..
Multistage rocket
A multistage (or multi-stage) rocket is, like any rocket, propelled by the recoil pressure of the burning gases it emits as it burns fuel.
What characterizes it as “multi-stage” is that it successively jettisons one or more stages as they become empty.
It is effectively one or more rockets (stages) stacked on top of or attached next to each other (”parallel staging”); in order to reduce the total amount of mass which needs to be accelerated to the final speed/height.
Generally each stage consists of one or more motors, plus fuel and oxidiser tanks for a liquid rocket or the casing for a solid rocket.
In rocketry, this concept is known as staging.
Solid or liquid rocket Boosters are often used for parallel staging schemes and all motors are ignited at launch..
Lunar space elevator
A lunar space elevator (also called a moonstalk) is a proposed cable running from the surface of the Moon into space.
It is similar in concept to the better known Earth space elevator idea (a cable suspended above Earth, with its center of gravity in geostationary orbit).
It would instead be constructed with its center of gravity in a stationary position above the surface of the Moon, providing a controlled means to transport people and/or materials between the surface and lunar orbit. A lunar elevator could massively reduce the costs for reliably and cheaply soft-landing equipment on the lunar surface..

“This article is brought to you by Gus Woltmann”.

Space Missions

admin — Fri, 25 Sep 2009 13:14:11 +0000

Phoenix (spacecraft)
The Phoenix is a planned multi-agency Mars lander, headed by the University of Arizona’s Lunar and Planetary Laboratory, under the direction of NASA, scheduled to launch on August 3, 2007.
It is a partnership of universities, NASA, the Canadian Space Agency, and the aerospace industry.
Phoenix is scheduled to land in May 2008 in the planet’s water-ice-rich northern polar region.
It will dig its robotic arm into the arctic terrain searching for information on the history of water, and search for environments suitable for microbial life on Mars.
The mission has two goals.
One is to study the geologic history of water, the key to unlocking the story of past climate change.
The second is to search for evidence of a habitable zone that may exist in the ice-soil boundary, the “biological paydirt.” The Phoenix’s instruments are suitable for uncovering information on the geological and possibly biological history of the martian arctic.
Because the Phoenix will be the first mission to return data from either of the poles, it will contribute to NASA’s main strategy for Mars exploration, “Follow the water”..
Exploration of Mars
The exploration of Mars has been an important part of the space exploration missions of the Soviet Union (later Russia), the United States, Europe, and Japan.
Dozens of unmanned spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s.
These missions were aimed at gathering data and answering questions about the red planet and its past that may yield further insight into Earth’s past, present, and future..
NASA
The National Aeronautics and Space Administration (NASA), which was established in 1958, is the agency responsible for the public space program of the United States of America.
NASA’s vision is “to improve life here, extend life to there, and to find life beyond”.
Its mission is “to understand and protect our home planet; to explore the Universe and search for life; and to inspire the next generation of explorers”..
Voyager program
The Voyager program consisted of a pair of unmanned scientific probes, Voyager 1 and Voyager 2, launched in 1977.
They were sent to study Jupiter and Saturn, using an advantageous planetary alignment of the late 1970s..

“This article is brought to you by Gus Woltmann”.

Space Exploration

admin — Fri, 25 Sep 2009 13:11:09 +0000

Space observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects.
A large number of observatories have been launched into orbit, and most of them have greatly enhanced our knowledge of the cosmos.
Performing astronomy from the Earth’s surface is limited by the filtering and distortion of electromagnetic radiation due to the Earth’s atmosphere.
This makes it desirable to place astrononomical observation devices into space.
As a telescope orbits the Earth outside the atmosphere it is subject neither to twinkling (distortion due to thermal turbulences of the air) nor to light pollution from artificial light sources on the Earth.
But space-based astronomy is even more important for frequency ranges which are outside of the optic window and the radio window, the only two wavelength ranges of the electromagnetic spectrum that are not severely attenuated by the atmosphere.
For example, X-ray astronomy is nearly impossible when done from the Earth, and has reached its current important stand within astronomy only due to orbiting satellites with X-ray telescopes such as the Chandra observatory or XMM-Newton observatory.
Infrared and ultraviolet are also greatly blocked..
Exploration of Mars
The exploration of Mars has been an important part of the space exploration missions of the Soviet Union (later Russia), the United States, Europe, and Japan.
Dozens of unmanned spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s.
These missions were aimed at gathering data and answering questions about the red planet and its past that may yield further insight into Earth’s past, present, and future..
Phoenix (spacecraft)
The Phoenix is a planned multi-agency Mars lander, headed by the University of Arizona’s Lunar and Planetary Laboratory, under the direction of NASA, scheduled to launch on August 3, 2007.
It is a partnership of universities, NASA, the Canadian Space Agency, and the aerospace industry.
Phoenix is scheduled to land in May 2008 in the planet’s water-ice-rich northern polar region.
It will dig its robotic arm into the arctic terrain searching for information on the history of water, and search for environments suitable for microbial life on Mars.
The mission has two goals.
One is to study the geologic history of water, the key to unlocking the story of past climate change.
The second is to search for evidence of a habitable zone that may exist in the ice-soil boundary, the “biological paydirt.” The Phoenix’s instruments are suitable for uncovering information on the geological and possibly biological history of the martian arctic.
Because the Phoenix will be the first mission to return data from either of the poles, it will contribute to NASA’s main strategy for Mars exploration, “Follow the water”..
NASA
The National Aeronautics and Space Administration (NASA), which was established in 1958, is the agency responsible for the public space program of the United States of America.
NASA’s vision is “to improve life here, extend life to there, and to find life beyond”.
Its mission is “to understand and protect our home planet; to explore the Universe and search for life; and to inspire the next generation of explorers”..

“This article is brought to you by Gus Woltmann”.

Satellites

admin — Fri, 25 Sep 2009 13:09:21 +0000

Geosynchronous orbit
A geosynchronous orbit is a geocentric orbit that has the same orbital period as the sidereal rotation period of the Earth.
It has a semi-major axis of 42,164 km (26,200 miles).
In the special case of the geostationary orbit, an observer on the ground would not perceive the satellite as moving and would see it as a fixed point in the sky.
Such orbits are useful for telecommunications relays.
In the more general case, when the orbit has some inclination and/or eccentricity, the satellite would appear to describe a more or less distorted figure-eight in the sky, and would rest above the same spots of the Earth’s surface once per sidereal day. Synchronous orbits exist around all moons, planets, stars and black holes —unless they rotate so slowly that the orbit would be outside their Hill sphere.
Most inner moons of planets have synchronous rotation, so their synchronous orbits are, in practice, limited to their leading and trailing Lagrange points.
Objects with chaotic rotations (such as Hyperion) are also problematic, as their synchronous orbits keep changing unpredictably.
If a geosynchronous orbit is circular and equatorial then it is also a geostationary orbit, and will maintain the same position relative to the Earth’s surface.
If one could see a satellite in geostationary orbit, it would appear to hover at the same point in the sky, i.e., not exhibit diurnal motion, while one would see the Sun, Moon, and stars traverse the heavens behind it..
Space observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects.
A large number of observatories have been launched into orbit, and most of them have greatly enhanced our knowledge of the cosmos.
Performing astronomy from the Earth’s surface is limited by the filtering and distortion of electromagnetic radiation due to the Earth’s atmosphere.
This makes it desirable to place astrononomical observation devices into space.
As a telescope orbits the Earth outside the atmosphere it is subject neither to twinkling (distortion due to thermal turbulences of the air) nor to light pollution from artificial light sources on the Earth.
But space-based astronomy is even more important for frequency ranges which are outside of the optic window and the radio window, the only two wavelength ranges of the electromagnetic spectrum that are not severely attenuated by the atmosphere.
For example, X-ray astronomy is nearly impossible when done from the Earth, and has reached its current important stand within astronomy only due to orbiting satellites with X-ray telescopes such as the Chandra observatory or XMM-Newton observatory.
Infrared and ultraviolet are also greatly blocked..
Space debris
Space debris or orbital debris, also called space junk and space waste, are the objects in orbit around Earth created by man that no longer serve any useful purpose.
They consist of everything from entire spent rocket stages and defunct satellites to explosion fragments, paint flakes, dust and slag from solid rocket motors, coolant released by RORSAT nuclear powered satellites, and other small particles..
Equatorial bulge
An equatorial bulge is a planetological term which describes a bulge which a planet may have around its equator, distorting it into an oblate spheroid.
Because of a planet’s equatorial bulge, its gravitational field is weaker at the equator than at its poles..

“This article is brought to you by Gus Woltmann”.

NASA

admin — Fri, 25 Sep 2009 13:06:30 +0000

Space observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects.
A large number of observatories have been launched into orbit, and most of them have greatly enhanced our knowledge of the cosmos.
Performing astronomy from the Earth’s surface is limited by the filtering and distortion of electromagnetic radiation due to the Earth’s atmosphere.
This makes it desirable to place astrononomical observation devices into space.
As a telescope orbits the Earth outside the atmosphere it is subject neither to twinkling (distortion due to thermal turbulences of the air) nor to light pollution from artificial light sources on the Earth.
But space-based astronomy is even more important for frequency ranges which are outside of the optic window and the radio window, the only two wavelength ranges of the electromagnetic spectrum that are not severely attenuated by the atmosphere.
For example, X-ray astronomy is nearly impossible when done from the Earth, and has reached its current important stand within astronomy only due to orbiting satellites with X-ray telescopes such as the Chandra observatory or XMM-Newton observatory.
Infrared and ultraviolet are also greatly blocked..
NASA
The National Aeronautics and Space Administration (NASA), which was established in 1958, is the agency responsible for the public space program of the United States of America.
NASA’s vision is “to improve life here, extend life to there, and to find life beyond”.
Its mission is “to understand and protect our home planet; to explore the Universe and search for life; and to inspire the next generation of explorers”..
Phoenix (spacecraft)
The Phoenix is a planned multi-agency Mars lander, headed by the University of Arizona’s Lunar and Planetary Laboratory, under the direction of NASA, scheduled to launch on August 3, 2007.
It is a partnership of universities, NASA, the Canadian Space Agency, and the aerospace industry.
Phoenix is scheduled to land in May 2008 in the planet’s water-ice-rich northern polar region.
It will dig its robotic arm into the arctic terrain searching for information on the history of water, and search for environments suitable for microbial life on Mars.
The mission has two goals.
One is to study the geologic history of water, the key to unlocking the story of past climate change.
The second is to search for evidence of a habitable zone that may exist in the ice-soil boundary, the “biological paydirt.” The Phoenix’s instruments are suitable for uncovering information on the geological and possibly biological history of the martian arctic.
Because the Phoenix will be the first mission to return data from either of the poles, it will contribute to NASA’s main strategy for Mars exploration, “Follow the water”..
Exploration of Mars
The exploration of Mars has been an important part of the space exploration missions of the Soviet Union (later Russia), the United States, Europe, and Japan.
Dozens of unmanned spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s.
These missions were aimed at gathering data and answering questions about the red planet and its past that may yield further insight into Earth’s past, present, and future..

“This article is brought to you by Gus Woltmann”.

ESA

admin — Fri, 25 Sep 2009 13:03:20 +0000

Space observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects.
A large number of observatories have been launched into orbit, and most of them have greatly enhanced our knowledge of the cosmos.
Performing astronomy from the Earth’s surface is limited by the filtering and distortion of electromagnetic radiation due to the Earth’s atmosphere.
This makes it desirable to place astrononomical observation devices into space.
As a telescope orbits the Earth outside the atmosphere it is subject neither to twinkling (distortion due to thermal turbulences of the air) nor to light pollution from artificial light sources on the Earth.
But space-based astronomy is even more important for frequency ranges which are outside of the optic window and the radio window, the only two wavelength ranges of the electromagnetic spectrum that are not severely attenuated by the atmosphere.
For example, X-ray astronomy is nearly impossible when done from the Earth, and has reached its current important stand within astronomy only due to orbiting satellites with X-ray telescopes such as the Chandra observatory or XMM-Newton observatory.
Infrared and ultraviolet are also greatly blocked..
European Space Agency
The European Space Agency (ESA), established in 1975, is an inter-governmental organisation dedicated to exploration of space with currently 17 member states.
ESA has ambitious space plans that may be divided into three large categories.
First, ESA will maintain its scientific and research projects (e.g.
tests and developments of new propulsion systems), try to find ways to reduce costs for their rocket fleet while enhancing their capacities, honour its commitments regarding the ISS and engage in further space exploration like the Venus Express mission that was launched in late 2005.
The second category has many parallels to NASA’s plans and constitutes of astronomy-space missions such as the Planck Surveyor studying the cosmic microwave background (2008), the Herschel space observatory (2008), Corot that will be a milestone in the search for extrasolar planets and is due to launch in 2007..
Ion thruster propulsion system
An ion thruster (or ion drive), one of several types of spacecraft propulsion, uses beams of ions – electrically charged atoms or molecules – for propulsion.
The precise method for accelerating the ions may vary, but all designs take advantage of the charge-to-mass ratio of ions to accelerate them to very high velocities using a high electric field.
Ion thrusters are therefore able to achieve high specific impulse, reducing the amount of reaction mass required, but increasing the amount of power required compared to chemical rockets.
Ion thrusters can deliver one order of magnitude greater propellant efficiency than traditional liquid fuel rocket engines, but are constrained to very low accelerations by the power/weight ratios of available power systems..
Space debris
Space debris or orbital debris, also called space junk and space waste, are the objects in orbit around Earth created by man that no longer serve any useful purpose.
They consist of everything from entire spent rocket stages and defunct satellites to explosion fragments, paint flakes, dust and slag from solid rocket motors, coolant released by RORSAT nuclear powered satellites, and other small particles..

“This article is brought to you by Gus Woltmann”.

Xena

admin — Fri, 25 Sep 2009 12:50:53 +0000

Dysnomia (moon of Eris)
Dysnomia, is a moon of the dwarf planet Eris.
The satellite is about 60 times fainter than Eris, and its diameter is estimated to be approximately eight times smaller.
Astronomers now know that three of the four brightest Kuiper belt objects (KBOs) have satellites, while among the fainter members of the belt only about 10% are known to have satellites..
Eris (dwarf planet)
Eris is the largest known dwarf planet in the solar system.
It is a trans-Neptunian object (TNO), orbiting the Sun in a region of space known as the scattered disc, just beyond the Kuiper belt, and accompanied by at least one moon, Dysnomia.
Eris’ size resulted in its discoverers and NASA labelling it the solar system’s tenth planet.
This, along with the prospect of other similarly sized objects being discovered in the future, stimulated the International Astronomical Union (IAU) to define the term “planet” more precisely.
Under a new definition approved on August 24, 2006, Eris was designated a “dwarf planet” along with Pluto and Ceres..
Definition of planet
The definition of “planet” has for some time been the subject of intense debate.
Although the word dates back thousands of years, no officially decreed scientific definition of “planet” existed before the early 21st century.
Until the beginning of the 1990s, there was little need for one, as astronomers had only a single sample of planets in solar system to study, and one small enough for its many irregularities to be dealt with individually. However, after 1992 and the discovery of the myriad tiny worlds beyond the orbit of Neptune, the size of the sample rose from nine to at least several dozen.
Following the discovery of the first extrasolar planet beyond our solar system in 1992, the number of samples has now reached hundreds.
These revelations not only increased the number of potential planets, but, in their variety and peculiarity (some nearly large enough to be stars, others smaller than our Moon) challenged long perceived notions of what a planet could be..
Asteroid belt
The asteroid belt is a region of the solar system falling roughly between the planets Mars and Jupiter where the greatest concentration of asteroid orbits can be found.
Despite popular imagery, the asteroid belt is mostly empty.
The asteroids are spread over such a large volume that it would be highly improbable to reach an asteroid without aiming carefully. Nonetheless, tens of thousands of asteroids are currently known, and estimates of the total number range in the millions.
About 220 of them are larger than 100 km.
The biggest asteroid belt member, and the only dwarf planet found there, is Ceres, which is about 1000 km across.
The total mass of the Asteroid belt is estimated to be 3.0 to 3.6×1021 kilograms, which is 4 percent of the Earth’s Moon.
Of that total mass, one third is accounted for by Ceres alone. The high population makes for a very active environment, where collisions between asteroids occur very often (in astronomical terms).
A collision may fragment an asteroid in numerous small pieces (leading to the formation of a new asteroid family), or may glue two asteroids together if it occurs at low relative speeds.
After five billion years, the current Asteroid belt population bears little resemblance to the original one..

“This article is brought to you by Gus Woltmann”.

Venus

admin — Fri, 25 Sep 2009 12:48:40 +0000

Transit of Venus
A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and the Earth, obscuring a small portion of the Sun’s disc..
Deimos (moon)
Deimos is probably an asteroid that was perturbed by Jupiter into an orbit that allowed it to be captured by Mars, though this hypothesis is still in some dispute.
Like most bodies of its size, Deimos is highly nonspherical with dimensions of 15 by 12 by 10 km. Deimos is composed of rock rich in carbonaceous material, much like C-type asteroids and carbonaceous chondrite meteorites.
It is cratered, but the surface is noticeably smoother than that of Phobos, caused by the partial filling of craters with regolith.
The two largest craters, Swift and Voltaire, measure about 3 kilometres across. As seen from Deimos, Mars would be 1000 times larger and 400 times brighter than the full Moon as seen from Earth, taking up a full 1/11 of the width of a celestial hemisphere..
Neptune’s natural satellites
Neptune has 13 known moons.
The largest by far is Triton, discovered by William Lassell just 17 days after the discovery of Neptune itself.
It took a hundred years to discover the second, Nereid.
Triton orbits Neptune on a circular but retrograde orbit.
While retrograde orbits are common among distant irregular satellites, Triton is a unique case of retrograde moon so close to its planet. The third largest moon of Neptune, Nereid follows a prograde but the most eccentric orbit among the moons of the solar system, being at its apocenter more than 7 times further from the planet than at its pericenter. Two natural satellites discovered in 2002 and 2003, Psamathe and S/2002 N 4, have the largest orbits of any natural satellites discovered in the Solar system to date.
They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. It is likely that Neptune’s inner satellites are not the original bodies that formed with Neptune but accreted rubble from the havoc that was wreaked after Triton’s capture.
Triton’s original captured orbit would have been highly eccentric, and caused chaotic perturbations in the orbits of the original inner Neptunian satellites, caussing them to collide and become reduced to a rubble disc.
Only after Triton’s orbit became circularised did some of the rubble disc re-accrete into the present-day satellites.
The mechanism of the Triton’s capture have been the subject of a few theories over the years.
The most recent postulates that Triton was captured in a three body encounter.
In this scenario, Triton is the surviving member of a binary object1 disrupted by the encounter with Neptune..
Asteroid belt
The asteroid belt is a region of the solar system falling roughly between the planets Mars and Jupiter where the greatest concentration of asteroid orbits can be found.
Despite popular imagery, the asteroid belt is mostly empty.
The asteroids are spread over such a large volume that it would be highly improbable to reach an asteroid without aiming carefully. Nonetheless, tens of thousands of asteroids are currently known, and estimates of the total number range in the millions.
About 220 of them are larger than 100 km.
The biggest asteroid belt member, and the only dwarf planet found there, is Ceres, which is about 1000 km across.
The total mass of the Asteroid belt is estimated to be 3.0 to 3.6×1021 kilograms, which is 4 percent of the Earth’s Moon.
Of that total mass, one third is accounted for by Ceres alone. The high population makes for a very active environment, where collisions between asteroids occur very often (in astronomical terms).
A collision may fragment an asteroid in numerous small pieces (leading to the formation of a new asteroid family), or may glue two asteroids together if it occurs at low relative speeds.
After five billion years, the current Asteroid belt population bears little resemblance to the original one..

“This article is brought to you by Gus Woltmann”.

Uranus

admin — Fri, 25 Sep 2009 12:46:50 +0000

Uranus’ natural satellites
Uranus has 27 known moons.
The first two moons (Titania and Oberon) were discovered by William Herschel on March 13, 1787.
Two more moons (Ariel and Umbriel) were discovered by William Lassell in 1851.
In 1852, Herschel’s son John Herschel gave the four then-known moons their names.
In 1948 Gerard Kuiper discovered the moon Miranda. The flyby of the Voyager 2 space probe in January 1986 led to the discovery of a further 10 inner moons, and another satellite Perdita was later found after studying old Voyager photographs.
Two more small inner moons were discovered by astronomers using the Hubble Space Telescope.
Until 1997, Uranus was the only giant planet with no known irregular satellites.
Since then, nine distant irregular moons have been identified using ground-based telescopes. The region between the main rings and Miranda appears to be very crowded.
The system is chaotic and apparently unstable, and simulations show that the moons may perturb each other into crossing orbits which may result in collisions between the moons..
Neptune’s natural satellites
Neptune has 13 known moons.
The largest by far is Triton, discovered by William Lassell just 17 days after the discovery of Neptune itself.
It took a hundred years to discover the second, Nereid.
Triton orbits Neptune on a circular but retrograde orbit.
While retrograde orbits are common among distant irregular satellites, Triton is a unique case of retrograde moon so close to its planet. The third largest moon of Neptune, Nereid follows a prograde but the most eccentric orbit among the moons of the solar system, being at its apocenter more than 7 times further from the planet than at its pericenter. Two natural satellites discovered in 2002 and 2003, Psamathe and S/2002 N 4, have the largest orbits of any natural satellites discovered in the Solar system to date.
They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. It is likely that Neptune’s inner satellites are not the original bodies that formed with Neptune but accreted rubble from the havoc that was wreaked after Triton’s capture.
Triton’s original captured orbit would have been highly eccentric, and caused chaotic perturbations in the orbits of the original inner Neptunian satellites, caussing them to collide and become reduced to a rubble disc.
Only after Triton’s orbit became circularised did some of the rubble disc re-accrete into the present-day satellites.
The mechanism of the Triton’s capture have been the subject of a few theories over the years.
The most recent postulates that Triton was captured in a three body encounter.
In this scenario, Triton is the surviving member of a binary object1 disrupted by the encounter with Neptune..
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter.
Gas giants may have a rocky or metallic core—in fact, such a core is thought to be required for a gas giant to form—but the majority of its mass is in the form of the gases hydrogen and helium, with traces of water, methane, ammonia, and other hydrogen compounds.
Unlike rocky planets, which have a clearly defined difference between atmosphere and surface, gas giants do not have a well-defined surface; their atmospheres simply become gradually denser toward the core, perhaps with liquid or liquid-like states in between.
One cannot “land on” such planets in the traditional sense.
There are four gas giants in our solar system: Jupiter, Saturn, Uranus, and Neptune..
Voyager program
The Voyager program consisted of a pair of unmanned scientific probes, Voyager 1 and Voyager 2, launched in 1977.
They were sent to study Jupiter and Saturn, using an advantageous planetary alignment of the late 1970s..

“This article is brought to you by Gus Woltmann”.

Sun

admin — Fri, 25 Sep 2009 12:44:12 +0000

Solar flare
A solar flare is a violent explosion in the Sun’s atmosphere with an energy equivalent to tens of millions of hydrogen bombs.
Solar flares take place in the solar corona and chromosphere, heating plasma to tens of millions of kelvins and accelerating the resulting electrons, protons and heavier ions to near the speed of light.
They produce electromagnetic radiation across the electromagnetic spectrum at all wavelengths from long-wave radio to the shortest wavelength gamma rays.
Most flares occur around sunspots, where intense magnetic fields emerge from the Sun’s surface into the corona.
The energy efficiency associated with solar flares may take several hours or even days to build up, but most flares take only a matter of minutes to release their energy..
Corona
In astronomy, a corona is the luminous plasma “atmosphere” of the Sun or other celestial body, extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph..
Solar radiation
Solar radiation is radiant energy emitted by the sun, particularly electromagnetic energy.
About half of the radiation is in the visible short-wave part of the electromagnetic spectrum.
The other half is mostly in the near-infrared part, with some in the ultraviolet part of the spectrum [1].
The portion of this ultraviolet radiation that is not absorbed by the atmosphere produces a suntan or a sunburn on people who have been in sunlight for extended periods of time..
Sunspot
A sunspot is a region on the Sun’s surface (photosphere) that is marked by a lower temperature than its surroundings and intense magnetic activity, which inhibits convection, forming areas of low surface temperature.
Although they are blindingly bright at temperatures of roughly 4000-4500 K, the contrast with the surrounding material at some 5700 K leaves them clearly visible as dark spots.
If they were isolated from the surrounding photosphere they would be brighter than an electric arc.
Sunspot numbers have been recorded since 1700 AD and estimated back to 11,000 BP.
The recent trend is upward from 1900 to the 1960s, then somewhat downward.
The Sun was last similarly active over 8,000 years ago..

“This article is brought to you by Gus Woltmann”.

Solar System

admin — Fri, 25 Sep 2009 12:40:57 +0000

Neptune’s natural satellites
Neptune has 13 known moons.
The largest by far is Triton, discovered by William Lassell just 17 days after the discovery of Neptune itself.
It took a hundred years to discover the second, Nereid.
Triton orbits Neptune on a circular but retrograde orbit.
While retrograde orbits are common among distant irregular satellites, Triton is a unique case of retrograde moon so close to its planet. The third largest moon of Neptune, Nereid follows a prograde but the most eccentric orbit among the moons of the solar system, being at its apocenter more than 7 times further from the planet than at its pericenter. Two natural satellites discovered in 2002 and 2003, Psamathe and S/2002 N 4, have the largest orbits of any natural satellites discovered in the Solar system to date.
They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. It is likely that Neptune’s inner satellites are not the original bodies that formed with Neptune but accreted rubble from the havoc that was wreaked after Triton’s capture.
Triton’s original captured orbit would have been highly eccentric, and caused chaotic perturbations in the orbits of the original inner Neptunian satellites, caussing them to collide and become reduced to a rubble disc.
Only after Triton’s orbit became circularised did some of the rubble disc re-accrete into the present-day satellites.
The mechanism of the Triton’s capture have been the subject of a few theories over the years.
The most recent postulates that Triton was captured in a three body encounter.
In this scenario, Triton is the surviving member of a binary object1 disrupted by the encounter with Neptune..
Dysnomia (moon of Eris)
Dysnomia, is a moon of the dwarf planet Eris.
The satellite is about 60 times fainter than Eris, and its diameter is estimated to be approximately eight times smaller.
Astronomers now know that three of the four brightest Kuiper belt objects (KBOs) have satellites, while among the fainter members of the belt only about 10% are known to have satellites..
Uranus’ natural satellites
Uranus has 27 known moons.
The first two moons (Titania and Oberon) were discovered by William Herschel on March 13, 1787.
Two more moons (Ariel and Umbriel) were discovered by William Lassell in 1851.
In 1852, Herschel’s son John Herschel gave the four then-known moons their names.
In 1948 Gerard Kuiper discovered the moon Miranda. The flyby of the Voyager 2 space probe in January 1986 led to the discovery of a further 10 inner moons, and another satellite Perdita was later found after studying old Voyager photographs.
Two more small inner moons were discovered by astronomers using the Hubble Space Telescope.
Until 1997, Uranus was the only giant planet with no known irregular satellites.
Since then, nine distant irregular moons have been identified using ground-based telescopes. The region between the main rings and Miranda appears to be very crowded.
The system is chaotic and apparently unstable, and simulations show that the moons may perturb each other into crossing orbits which may result in collisions between the moons..
Asteroid belt
The asteroid belt is a region of the solar system falling roughly between the planets Mars and Jupiter where the greatest concentration of asteroid orbits can be found.
Despite popular imagery, the asteroid belt is mostly empty.
The asteroids are spread over such a large volume that it would be highly improbable to reach an asteroid without aiming carefully. Nonetheless, tens of thousands of asteroids are currently known, and estimates of the total number range in the millions.
About 220 of them are larger than 100 km.
The biggest asteroid belt member, and the only dwarf planet found there, is Ceres, which is about 1000 km across.
The total mass of the Asteroid belt is estimated to be 3.0 to 3.6×1021 kilograms, which is 4 percent of the Earth’s Moon.
Of that total mass, one third is accounted for by Ceres alone. The high population makes for a very active environment, where collisions between asteroids occur very often (in astronomical terms).
A collision may fragment an asteroid in numerous small pieces (leading to the formation of a new asteroid family), or may glue two asteroids together if it occurs at low relative speeds.
After five billion years, the current Asteroid belt population bears little resemblance to the original one..

“This article is brought to you by Gus Woltmann”.

Saturn

admin — Fri, 25 Sep 2009 12:35:19 +0000

Saturn is the sixth planet from the Sun.
It is a gas giant, the second-largest planet in the solar system after Jupiter.
Saturn has a prominent system of rings, consisting of mostly ice particles with a smaller amount of rocky debris and dust..
Titan (moon)
Titan, or Saturn VI, is the largest moon of Saturn and the second largest moon in the solar system, after Jupiter’s moon Ganymede.
It is roughly 50% larger than Earth’s moon by diameter, and is larger by diameter and mass than all known dwarf planets.
It is also larger by diameter than the planet Mercury, though Mercury is more than twice as massive. Titan is the only moon in our solar system to have a dense atmosphere.
The atmosphere is 98.4% nitrogen.
Until very recently, this atmosphere inhibited understanding of Titan’s surface, but the moon is currently undergoing study by the Cassini-Huygens mission, and new information about it is accumulating.
On July 27, 2006, NASA confirmed the presence of hydrocarbon lakes in Titan’s north polar region.
At the surface, Titan’s temperature is about 94 K..
Saturn’s natural satellites
Saturn is currently known to have 56 moons, many of which were discovered very recently, and 3 additional un-confirmed, hypothetical moons.
However, a precise number of moons can never be given, as there is no objective dividing line between the anonymous orbiting fragments that form Saturn’s ring system and the larger objects that have already been named as moons..
Neptune’s natural satellites
Neptune has 13 known moons.
The largest by far is Triton, discovered by William Lassell just 17 days after the discovery of Neptune itself.
It took a hundred years to discover the second, Nereid.
Triton orbits Neptune on a circular but retrograde orbit.
While retrograde orbits are common among distant irregular satellites, Triton is a unique case of retrograde moon so close to its planet. The third largest moon of Neptune, Nereid follows a prograde but the most eccentric orbit among the moons of the solar system, being at its apocenter more than 7 times further from the planet than at its pericenter. Two natural satellites discovered in 2002 and 2003, Psamathe and S/2002 N 4, have the largest orbits of any natural satellites discovered in the Solar system to date.
They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. It is likely that Neptune’s inner satellites are not the original bodies that formed with Neptune but accreted rubble from the havoc that was wreaked after Triton’s capture.
Triton’s original captured orbit would have been highly eccentric, and caused chaotic perturbations in the orbits of the original inner Neptunian satellites, caussing them to collide and become reduced to a rubble disc.
Only after Triton’s orbit became circularised did some of the rubble disc re-accrete into the present-day satellites.
The mechanism of the Triton’s capture have been the subject of a few theories over the years.
The most recent postulates that Triton was captured in a three body encounter.
In this scenario, Triton is the surviving member of a binary object1 disrupted by the encounter with Neptune..

“This article is brought to you by Gus Woltmann”.

Pluto

admin — Fri, 25 Sep 2009 12:33:32 +0000

Dysnomia (moon of Eris)
Dysnomia, is a moon of the dwarf planet Eris.
The satellite is about 60 times fainter than Eris, and its diameter is estimated to be approximately eight times smaller.
Astronomers now know that three of the four brightest Kuiper belt objects (KBOs) have satellites, while among the fainter members of the belt only about 10% are known to have satellites..
Neptune’s natural satellites
Neptune has 13 known moons.
The largest by far is Triton, discovered by William Lassell just 17 days after the discovery of Neptune itself.
It took a hundred years to discover the second, Nereid.
Triton orbits Neptune on a circular but retrograde orbit.
While retrograde orbits are common among distant irregular satellites, Triton is a unique case of retrograde moon so close to its planet. The third largest moon of Neptune, Nereid follows a prograde but the most eccentric orbit among the moons of the solar system, being at its apocenter more than 7 times further from the planet than at its pericenter. Two natural satellites discovered in 2002 and 2003, Psamathe and S/2002 N 4, have the largest orbits of any natural satellites discovered in the Solar system to date.
They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. It is likely that Neptune’s inner satellites are not the original bodies that formed with Neptune but accreted rubble from the havoc that was wreaked after Triton’s capture.
Triton’s original captured orbit would have been highly eccentric, and caused chaotic perturbations in the orbits of the original inner Neptunian satellites, caussing them to collide and become reduced to a rubble disc.
Only after Triton’s orbit became circularised did some of the rubble disc re-accrete into the present-day satellites.
The mechanism of the Triton’s capture have been the subject of a few theories over the years.
The most recent postulates that Triton was captured in a three body encounter.
In this scenario, Triton is the surviving member of a binary object1 disrupted by the encounter with Neptune..
Charon (moon)
Charon, discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member.
With the discovery in 2005 of two other moons of Pluto (Nix and Hydra), Charon is now also referred to as Pluto I.
The New Horizons mission is scheduled to visit Charon and Pluto in July 2015.
Charon was discovered by astronomer James Christy on June 22, 1978 when he was examining highly magnified images of Pluto on photographic plates taken a couple of months before.
Christy noticed that a slight bulge appeared periodically.
Later, the bulge was confirmed on plates dating back to April 29, 1965..
Uranus’ natural satellites
Uranus has 27 known moons.
The first two moons (Titania and Oberon) were discovered by William Herschel on March 13, 1787.
Two more moons (Ariel and Umbriel) were discovered by William Lassell in 1851.
In 1852, Herschel’s son John Herschel gave the four then-known moons their names.
In 1948 Gerard Kuiper discovered the moon Miranda. The flyby of the Voyager 2 space probe in January 1986 led to the discovery of a further 10 inner moons, and another satellite Perdita was later found after studying old Voyager photographs.
Two more small inner moons were discovered by astronomers using the Hubble Space Telescope.
Until 1997, Uranus was the only giant planet with no known irregular satellites.
Since then, nine distant irregular moons have been identified using ground-based telescopes. The region between the main rings and Miranda appears to be very crowded.
The system is chaotic and apparently unstable, and simulations show that the moons may perturb each other into crossing orbits which may result in collisions between the moons..

“This article is brought to you by Gus Woltmann”.

Northern Lights

admin — Fri, 25 Sep 2009 12:31:26 +0000

Solar flare

A solar flare is a violent explosion in the Sun’s atmosphere with an energy equivalent to tens of millions of hydrogen bombs.

Solar flares take place in the solar corona and chromosphere, heating plasma to tens of millions of kelvins and accelerating the resulting electrons, protons and heavier ions to near the speed of light.

They produce electromagnetic radiation across the electromagnetic spectrum at all wavelengths from long-wave radio to the shortest wavelength gamma rays.

Most flares occur around sunspots, where intense magnetic fields emerge from the Sun’s surface into the corona.

The energy efficiency associated with solar flares may take several hours or even days to build up, but most flares take only a matter of minutes to release their energy.. Solar wind

A solar wind is a stream of charged particles (i.e., a plasma) which are ejected from the upper atmosphere of a star.

When originating from stars other than the Earth’s Sun, it is sometimes called a stellar wind.. Geomagnetic storm

A geomagnetic storm is a temporary disturbance of the Earth’s magnetosphere.

Associated with solar coronal mass ejections, coronal holes, or solar flares, a geomagnetic storm is caused by a solar wind shock wave which typically strikes the Earth’s magnetic field 24 to 36 hours after the event..

Solar radiation

Solar radiation is radiant energy emitted by the sun, particularly electromagnetic energy.

About half of the radiation is in the visible short-wave part of the electromagnetic spectrum.

The other half is mostly in the near-infrared part, with some in the ultraviolet part of the spectrum [1].

The portion of this ultraviolet radiation that is not absorbed by the atmosphere produces a suntan or a sunburn on people who have been in sunlight for extended periods of time..

“This article is brought to you by Gus Woltmann”.

Neptune

admin — Fri, 25 Sep 2009 12:29:19 +0000

Neptune is the eighth and outermost planet in our solar system.

It is the fourth-largest planet by diameter and the third-largest by mass; Neptune is 17 times the mass of Earth and is slightly more massive than its near twin Uranus which is 14 Earth Masses, but slightly smaller due to its higher density.

Neptune’s atmosphere is primarily composed of hydrogen and helium, with traces of methane that account for the planet’s blue appearance.

Neptune’s blue colour is much more vivid than that of Uranus, which has a similar amount of methane, so an unknown component is presumed to cause Neptune’s intense color.

Neptune also has the strongest winds of any planet in the solar system, with estimates as high as 2,500 km/h or 1,500 mph..

“This article is brought to you by Gus Woltmann”.

Moon

admin — Fri, 25 Sep 2009 12:26:24 +0000

Lunar space elevator
A lunar space elevator (also called a moonstalk) is a proposed cable running from the surface of the Moon into space.
It is similar in concept to the better known Earth space elevator idea (a cable suspended above Earth, with its center of gravity in geostationary orbit).
It would instead be constructed with its center of gravity in a stationary position above the surface of the Moon, providing a controlled means to transport people and/or materials between the surface and lunar orbit. A lunar elevator could massively reduce the costs for reliably and cheaply soft-landing equipment on the lunar surface..
Eclipse
An eclipse is an astronomical event that occurs when one celestial object moves into the shadow of another.
The term is most often used to describe either a solar eclipse, when the Moon’s shadow crosses Earth’s surface, or a lunar eclipse, when the Moon moves into the shadow of Earth..
Buzz Aldrin
Colonel Buzz Aldrin, Sc.D (born January 20, 1930 as Edwin Eugene Aldrin, Jr.) is an American pilot and astronaut who became the second human to set foot on the Moon (after Neil Armstrong) during the Apollo 11 mission, the first manned lunar landing..
Moon
The Moon is Earth’s only natural satellite.
The average distance from the Earth to the Moon is 384,399 kilometres (238,854 mi), which is about 30 times the diameter of the Earth.
At this distance, it takes sunlight reflected from the lunar surface approximately 1.3 seconds to reach Earth.
The Moon’s diameter is 3,474 kilometres (2,159 mi), which is about 3.7 times smaller than the Earth, making it the Solar System’s fifth largest moon, both by diameter and mass, ranking behind Ganymede, Titan, Callisto, and Io..

“This article is brought to you by Gus Woltmann”.

Mercury

admin — Fri, 25 Sep 2009 12:24:30 +0000

Mercury (planet)
Mercury is the innermost and smallest planet in the solar system, orbiting the Sun once every 88 days.
It ranges in brightness from about −2.0 to 5.5 in apparent magnitude, but is not easily seen; its greatest angular separation from the Sun (greatest elongation) is only 28.3° (it can only be seen in twilight).
Comparatively little is known about the planet: the only spacecraft to approach Mercury was Mariner 10 from 1974 to 1975, which mapped only 40 to 45 percent of the planet’s surface. Physically, Mercury is similar in appearance to the Moon as it is heavily cratered.
It has no natural satellites and no substantial atmosphere.
The planet has a large iron core which generates a magnetic field about 1 percent as strong as that of the Earth.
Surface temperatures on Mercury range from about 90 to 700 K (-180 to 430°C) , with the subsolar point being the hottest and the bottoms of craters near the poles being the coldest..
NASA
The National Aeronautics and Space Administration (NASA), which was established in 1958, is the agency responsible for the public space program of the United States of America.
NASA’s vision is “to improve life here, extend life to there, and to find life beyond”.
Its mission is “to understand and protect our home planet; to explore the Universe and search for life; and to inspire the next generation of explorers”..
Venus
Venus is the second-closest planet to the Sun, orbiting it every 224.7 Earth days.
It is the brightest object in the night sky, except for the Moon, reaching an apparent magnitude of -4.6.
Venus reaches its maximum brightness shortly before sunrise or shortly after sunset, and is often referred to as the Morning Star or as the Evening Star.
A terrestrial planet, it is sometimes called Earth’s “sister planet”, as the two are similar in size and bulk composition.
The planet is covered with an opaque layer of highly reflective clouds and its surface cannot be seen from space in visible light, making it a subject of great speculation until some of its secrets were revealed by planetary science in the twentieth century.
Venus has the densest atmosphere of the terrestrial planets, consisting mostly of carbon dioxide, and the atmospheric pressure at the planet’s surface is 90 times that of the Earth..
Exploration of Mars
The exploration of Mars has been an important part of the space exploration missions of the Soviet Union (later Russia), the United States, Europe, and Japan.
Dozens of unmanned spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s.
These missions were aimed at gathering data and answering questions about the red planet and its past that may yield further insight into Earth’s past, present, and future..

“This article is brought to you by Gus Woltmann”.

Mars

admin — Fri, 25 Sep 2009 12:22:35 +0000

Exploration of Mars
The exploration of Mars has been an important part of the space exploration missions of the Soviet Union (later Russia), the United States, Europe, and Japan.
Dozens of unmanned spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s.
These missions were aimed at gathering data and answering questions about the red planet and its past that may yield further insight into Earth’s past, present, and future..
Phoenix (spacecraft)
The Phoenix is a planned multi-agency Mars lander, headed by the University of Arizona’s Lunar and Planetary Laboratory, under the direction of NASA, scheduled to launch on August 3, 2007.
It is a partnership of universities, NASA, the Canadian Space Agency, and the aerospace industry.
Phoenix is scheduled to land in May 2008 in the planet’s water-ice-rich northern polar region.
It will dig its robotic arm into the arctic terrain searching for information on the history of water, and search for environments suitable for microbial life on Mars.
The mission has two goals.
One is to study the geologic history of water, the key to unlocking the story of past climate change.
The second is to search for evidence of a habitable zone that may exist in the ice-soil boundary, the “biological paydirt.” The Phoenix’s instruments are suitable for uncovering information on the geological and possibly biological history of the martian arctic.
Because the Phoenix will be the first mission to return data from either of the poles, it will contribute to NASA’s main strategy for Mars exploration, “Follow the water”..
Deimos (moon)
Deimos is probably an asteroid that was perturbed by Jupiter into an orbit that allowed it to be captured by Mars, though this hypothesis is still in some dispute.
Like most bodies of its size, Deimos is highly nonspherical with dimensions of 15 by 12 by 10 km. Deimos is composed of rock rich in carbonaceous material, much like C-type asteroids and carbonaceous chondrite meteorites.
It is cratered, but the surface is noticeably smoother than that of Phobos, caused by the partial filling of craters with regolith.
The two largest craters, Swift and Voltaire, measure about 3 kilometres across. As seen from Deimos, Mars would be 1000 times larger and 400 times brighter than the full Moon as seen from Earth, taking up a full 1/11 of the width of a celestial hemisphere..
Meteorite
A meteorite is a small extraterrestrial body that impacts the Earth’s surface.
While in space they are called meteoroids, and while falling through Earth’s atmosphere they are called meteors.
These are small asteroids, approximately boulder-sized or less.
When it enters the atmosphere, air drag and friction cause the body to heat up and emit light, thus forming a fireball or shooting star..

“This article is brought to you by Gus Woltmann”.

Kuiper Belt

admin — Fri, 25 Sep 2009 12:20:15 +0000

Dysnomia (moon of Eris)
Dysnomia, is a moon of the dwarf planet Eris.
The satellite is about 60 times fainter than Eris, and its diameter is estimated to be approximately eight times smaller.
Astronomers now know that three of the four brightest Kuiper belt objects (KBOs) have satellites, while among the fainter members of the belt only about 10% are known to have satellites..
Eris (dwarf planet)
Eris is the largest known dwarf planet in the solar system.
It is a trans-Neptunian object (TNO), orbiting the Sun in a region of space known as the scattered disc, just beyond the Kuiper belt, and accompanied by at least one moon, Dysnomia.
Eris’ size resulted in its discoverers and NASA labelling it the solar system’s tenth planet.
This, along with the prospect of other similarly sized objects being discovered in the future, stimulated the International Astronomical Union (IAU) to define the term “planet” more precisely.
Under a new definition approved on August 24, 2006, Eris was designated a “dwarf planet” along with Pluto and Ceres..
Charon (moon)
Charon, discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member.
With the discovery in 2005 of two other moons of Pluto (Nix and Hydra), Charon is now also referred to as Pluto I.
The New Horizons mission is scheduled to visit Charon and Pluto in July 2015.
Charon was discovered by astronomer James Christy on June 22, 1978 when he was examining highly magnified images of Pluto on photographic plates taken a couple of months before.
Christy noticed that a slight bulge appeared periodically.
Later, the bulge was confirmed on plates dating back to April 29, 1965..
Definition of planet
The definition of “planet” has for some time been the subject of intense debate.
Although the word dates back thousands of years, no officially decreed scientific definition of “planet” existed before the early 21st century.
Until the beginning of the 1990s, there was little need for one, as astronomers had only a single sample of planets in solar system to study, and one small enough for its many irregularities to be dealt with individually. However, after 1992 and the discovery of the myriad tiny worlds beyond the orbit of Neptune, the size of the sample rose from nine to at least several dozen.
Following the discovery of the first extrasolar planet beyond our solar system in 1992, the number of samples has now reached hundreds.
These revelations not only increased the number of potential planets, but, in their variety and peculiarity (some nearly large enough to be stars, others smaller than our Moon) challenged long perceived notions of what a planet could be..

“This article is brought to you by Gus Woltmann”.

Jupiter

admin — Fri, 25 Sep 2009 12:18:25 +0000

Great Red Spot on Jupiter
The Great Red Spot is a persistent anticyclonic storm on the planet Jupiter, 22 degrees south of the equator, which has lasted at least 340 years.
The storm is large enough to be visible through Earth-based telescopes.
It was probably first observed by Cassini, who described it around 1665.
The oval object rotates counterclockwise, with a period of about 6 days.
The Great Red Spot’s dimensions are 24–40,000 km × 12–14,000 km.
It is large enough to contain two or three planets of Earth size.
The cloudtops of this storm are about 8 km above the surrounding cloudtops.
Storms such as this are not uncommon within the turbulent atmospheres of gas giants.
Jupiter also has white ovals and brown ovals, which are lesser unnamed storms.
White ovals tend to consist of relatively cool clouds within the upper atmosphere.
Brown ovals are warmer and located within the “normal cloud layer”.
Such storms can last hours or centuries..
Jupiter’s moons
Jupiter has 63 known natural satellites.
•
Although claims are made for the observation of one of Jupiter’s moons by Chinese astronomer Gan De in 364 BC, the first certain observations of Jupiter’s satellites are those of Galileo Galilei in 1610, who sighted the four large Galilean moons with his 33x telescope..
Jupiter
Jupiter is the fifth planet from the Sun and by far the largest within the solar system.
Jupiter is usually the fourth brightest object in the sky (after the Sun, the Moon and Venus); however at times Mars appears brighter than Jupiter. Jupiter is 2.5 times more massive than all the other planets combined, so massive that its barycenter with the Sun actually lies above the Sun’s surface (1.068 solar radii from the Sun’s center).
It is 318 times more massive than Earth, with a diameter 11 times that of Earth, and its volume is 1300 times as great as that of Earth.
Quite naturally, Jupiter’s gravitational influence has dominated the evolution of the solar system: some have described the solar system as consisting of the Sun, Jupiter, and assorted debris..
Neptune’s natural satellites
Neptune has 13 known moons.
The largest by far is Triton, discovered by William Lassell just 17 days after the discovery of Neptune itself.
It took a hundred years to discover the second, Nereid.
Triton orbits Neptune on a circular but retrograde orbit.
While retrograde orbits are common among distant irregular satellites, Triton is a unique case of retrograde moon so close to its planet. The third largest moon of Neptune, Nereid follows a prograde but the most eccentric orbit among the moons of the solar system, being at its apocenter more than 7 times further from the planet than at its pericenter. Two natural satellites discovered in 2002 and 2003, Psamathe and S/2002 N 4, have the largest orbits of any natural satellites discovered in the Solar system to date.
They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. It is likely that Neptune’s inner satellites are not the original bodies that formed with Neptune but accreted rubble from the havoc that was wreaked after Triton’s capture.
Triton’s original captured orbit would have been highly eccentric, and caused chaotic perturbations in the orbits of the original inner Neptunian satellites, caussing them to collide and become reduced to a rubble disc.
Only after Triton’s orbit became circularised did some of the rubble disc re-accrete into the present-day satellites.
The mechanism of the Triton’s capture have been the subject of a few theories over the years.
The most recent postulates that Triton was captured in a three body encounter.
In this scenario, Triton is the surviving member of a binary object1 disrupted by the encounter with Neptune..

“This article is brought to you by Gus Woltmann”.

Asteroids, Comets and Meteors

admin — Fri, 25 Sep 2009 12:16:12 +0000

Near-Earth object
Near-Earth objects (NEO) are asteroids, comets and large meteoroids whose orbit intersects Earth’s orbit and which may therefore pose a collision danger.
Due to their size and proximity, NEOs are also more easily accessible for spacecraft from Earth and are important for future scientific investigation and commercial development.
In fact, some near-Earth asteroids can be reached with a much smaller change in velocity than the Moon. In the United States, NASA has a congressional mandate to catalogue all NEOs that are at least 1 kilometer (0.6 miles) wide.
At this size and larger, an impacting NEO would cause catastrophic local damage and significant to severe global consequences.
Approximately 800 of these NEOs have been detected.
According to the most widely accepted estimates, there are still 200 more that have not been found yet.
The United States, European Union and other nations are currently scanning for NEOs in an effort called Spaceguard.
Currently efforts are under way to use an existing telescope in Australia to cover the approximately 30 percent of the sky that is not currently surveyed..
Meteorite
A meteorite is a small extraterrestrial body that impacts the Earth’s surface.
While in space they are called meteoroids, and while falling through Earth’s atmosphere they are called meteors.
These are small asteroids, approximately boulder-sized or less.
When it enters the atmosphere, air drag and friction cause the body to heat up and emit light, thus forming a fireball or shooting star..
Near-Earth asteroid
Near-Earth asteroids (NEAs) are asteroids whose orbits are close to Earth’s orbit.
Some NEAs’ orbits intersect Earth’s so they pose a collision danger.
On the other hand, NEAs are most easily accessible for spacecraft from Earth; in fact, some can be reached with much less delta-v than it takes to reach the Moon.
Two NEAs have been visited by spacecraft: 433 Eros, by NASA’s Near Earth Asteroid Rendezvous probe, and 25143 Itokawa, by the JAXA Hayabusa mission. Roughly 1000 near-Earth asteroids are known, ranging in size up to approximately 32 kilometres (1036 Ganymed).
Tens of thousands probably exist, with estimates placing the number of NEAs larger than one kilometer in diameter at up to 2,000. NEAs only survive in their orbits for 10 million to 100 million years.
They are eventually eliminated by orbital decay and accretion by the Sun, collisions with the inner planets, or by being ejected from the solar system by near misses with the planets.
Such processes should have eliminated them all long ago, so it is assumed they are resupplied on a regular basis by orbital migration of objects from the asteroid belt..
Torino Scale
The Torino Scale is a method for categorizing the impact hazard associated with near-Earth objects (NEOs) such as asteroids and comets..

“This article is brought to you by Gus Woltmann”.

Cosmology

admin — Fri, 25 Sep 2009 12:14:48 +0000

Shape of the Universe
The shape of the Universe is a subject of investigation within physical cosmology.
Cosmologists and astronomers describe the geometry of the Universe which includes both local geometry and global geometry.
The shape of the universe can be determined by measuring the average density of matter within it, assuming that all matter is evenly distributed, rather than the distortions caused by ‘dense’ objects such as galaxies.
This assumption is justified by the observations that, while the universe is “weakly” inhomogeneous and anisotropic (see the large-scale structure of the cosmos), it is on average homogeneous and isotropic.
Considerations of the geometry of the universe can be split into two parts; the local geometry relates to the observable universe, while the global geometry relates to the universe as a whole – including that which we can’t measure..
Supergiant
Supergiants are the most massive stars.
Supergiants can have masses from 10 to 70 solar masses and brightness from 30,000 up to hundreds of thousands times the solar luminosity.
They vary greatly in radii, usually from 30 to 500, or even in excess of 1000 solar radii.
Because of their extreme masses they have short lifespans of only 10 to 50 million years and are only observed in young cosmic structures such as open clusters, the arms of spiral galaxies, and in irregular galaxies.
They are less abundant in spiral galaxy bulges, and are not observed in elliptical galaxies, or globular clusters, all of which are believed to be composed of old stars.
Currently, the largest known stars in terms of physical size, not mass or luminosity, are the supergiants VV Cephei, V354 Cephei, KW Sagitarii, KY Cygni, and the Garnet Star..
Nucleosynthesis
Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons).
The primordial preexisting nucleons were formed from the quark-gluon plasma of the Big Bang as it cooled below ten million degrees.
This first process may be called nucleogenesis, the genesis of nucleons in the universe.
The subsequent nucleosynthesis of the elements (including all carbon, all oxygen, etc.) occurs primarily in stars either by nuclear fusion or nuclear fission..
Big Bang nucleosynthesis
In physical cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang.
It is believed to be responsible for the formation of hydrogen (H-1 or simply H), its isotope deuterium (H-2 or D), the helium isotopes He-3 and He-4, and the lithium isotope Li-7.
Big Bang nucleosynthesis begins about one minute after the Big Bang, when the universe has cooled enough to form stable protons and neutrons, after baryogenesis.
From simple thermodynamical arguments, one can calculate the fraction of protons and neutrons based on the temperature at this point.
This fraction is in favour of protons, because the higher mass of the neutron results in a spontaneous decay of neutrons to protons with a half-life of about 15 minutes..

“This article is brought to you by Gus Woltmann”.

Big Bang

admin — Fri, 25 Sep 2009 12:12:52 +0000

Nucleosynthesis
Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons).
The primordial preexisting nucleons were formed from the quark-gluon plasma of the Big Bang as it cooled below ten million degrees.
This first process may be called nucleogenesis, the genesis of nucleons in the universe.
The subsequent nucleosynthesis of the elements (including all carbon, all oxygen, etc.) occurs primarily in stars either by nuclear fusion or nuclear fission..
Shape of the Universe
The shape of the Universe is a subject of investigation within physical cosmology.
Cosmologists and astronomers describe the geometry of the Universe which includes both local geometry and global geometry.
The shape of the universe can be determined by measuring the average density of matter within it, assuming that all matter is evenly distributed, rather than the distortions caused by ‘dense’ objects such as galaxies.
This assumption is justified by the observations that, while the universe is “weakly” inhomogeneous and anisotropic (see the large-scale structure of the cosmos), it is on average homogeneous and isotropic.
Considerations of the geometry of the universe can be split into two parts; the local geometry relates to the observable universe, while the global geometry relates to the universe as a whole – including that which we can’t measure..
Big Bang nucleosynthesis
In physical cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang.
It is believed to be responsible for the formation of hydrogen (H-1 or simply H), its isotope deuterium (H-2 or D), the helium isotopes He-3 and He-4, and the lithium isotope Li-7.
Big Bang nucleosynthesis begins about one minute after the Big Bang, when the universe has cooled enough to form stable protons and neutrons, after baryogenesis.
From simple thermodynamical arguments, one can calculate the fraction of protons and neutrons based on the temperature at this point.
This fraction is in favour of protons, because the higher mass of the neutron results in a spontaneous decay of neutrons to protons with a half-life of about 15 minutes..
Ultimate fate of the universe
The ultimate fate of the universe is a subject of study in the field of cosmology.
Vying scientific theories predict whether the life of the universe is finite or infinite.
Current understanding of matter in the universe suggests that the universe must consist of dark energy and dark matter to explain the current rate of expansion.
Mainstream models of the universe currently predict that the universe will go on expanding at an accelerating rate..

“This article is brought to you by Gus Woltmann”.

Astrophysics

admin — Fri, 25 Sep 2009 12:11:04 +0000

Stars

admin — Fri, 25 Sep 2009 12:09:11 +0000

Red giant
A red giant is a large non-main sequence star of stellar classification K or M; so-named because of the reddish appearance of the cooler giant stars.
As Earth’s sun is of one solar mass, it is expected to become a red giant in about six billion years..
Supergiant
Supergiants are the most massive stars.
Supergiants can have masses from 10 to 70 solar masses and brightness from 30,000 up to hundreds of thousands times the solar luminosity.
They vary greatly in radii, usually from 30 to 500, or even in excess of 1000 solar radii.
Because of their extreme masses they have short lifespans of only 10 to 50 million years and are only observed in young cosmic structures such as open clusters, the arms of spiral galaxies, and in irregular galaxies.
They are less abundant in spiral galaxy bulges, and are not observed in elliptical galaxies, or globular clusters, all of which are believed to be composed of old stars.
Currently, the largest known stars in terms of physical size, not mass or luminosity, are the supergiants VV Cephei, V354 Cephei, KW Sagitarii, KY Cygni, and the Garnet Star..
Star cluster
Star clusters are groups of stars which are gravitationally bound.
Two distinct types of star cluster can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars, while open clusters generally contain less than a few hundred members, and are often very young..
Red supergiant star
Red supergiants are supergiant stars of spectral type K-M and a luminosity class of I.
They are the largest stars in the universe in terms of physical size, although they are not the most massive.
Stars with more than about 10 solar masses, after burning their hydrogen become red supergiants during their helium-burning phase.
These stars have very cool surface temperatures (3500-4500 K), and enormous radii.
The four largest known red supergiants in the Galaxy are Mu Cephei, KW Sagitarii, V354 Cephei, and KY Cygni, which all have radii about 1500 times that of the sun (about 7 astronomical units, or 7 times as far as the Earth is from the sun).
The radius of most red giants is between 200 and 800 times that of the sun, which is still enough to reach from the sun to Earth and beyond..

“This article is brought to you by Gus Woltmann”.

Nebulae

admin — Fri, 25 Sep 2009 12:07:40 +0000

Orion Nebula
The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a glowing emission nebula with a greenish hue and is situated below Orion’s Belt.
It is one of the brightest nebulae visible to the naked eye in the night sky.
M42 is one of the brightest diffuse nebula that can be seen in the night sky..
Planetary nebula
A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives.
They are in fact unrelated to planets; the name originates from a supposed similarity in appearance to giant planets.
They are a short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.
About 1,500 are known to exist in the Milky Way Galaxy.
Planetary nebulae are important objects in astronomy because they play a crucial role in the chemical evolution of the galaxy, returning material to the interstellar medium which has been enriched in heavy elements and other products of nucleosynthesis (such as carbon, nitrogen, oxygen and calcium).
In other galaxies, planetary nebulae may be the only objects observable enough to yield useful information about chemical abundances..
Interstellar medium
The interstellar medium (or ISM) is the name astronomers give to the tenuous gas and dust that pervade interstellar space.
Whilst the ISM refers to the matter (interstellar matter, also abbreviated by ISM) that exists between the stars within a galaxy, the energy, in the form of electromagnetic radiation, that occupies the same volume is called the interstellar radiation field (or ISRF). The ISM consists of an extremely dilute (by terrestrial standards) plasma, gas and dust, consisting of a mixture of ions, atoms, molecules, larger dust grains, electromagnetic radiation, cosmic rays, and magnetic fields.
The matter consists of about 99% gas and 1% dust by mass.
It fills interstellar space.
This mixture is usually extremely tenuous, with typical gas densities ranging from a few hundred to a few hundred million particles per cubic meter.
As a result of primordial nucleosynthesis, the gas is roughly 90% hydrogen and 10% helium by number, with additional elements (”metals” in astronomical parlance) present in trace amounts. The ISM plays a crucial role in astrophysics precisely because of its intermediate role between stellar and galactic scales.
Stars form within the densest regions of the ISM, molecular clouds, and replenish the ISM with matter and energy through planetary nebulae, stellar winds, and supernovae.
In turn, this interplay between stars and the ISM helps determine the rate at which a galaxy depletes its gaseous content, and therefore its lifespan of active star formation..
Stellar evolution
In astronomy, stellar evolution is the sequence of changes that a star undergoes during its lifetime; the hundreds of thousands, millions or billions of years during which it emits light and heat.
Over the course of that time, the star will change radically..

“This article is brought to you by Gus Woltmann”.

Galaxies

admin — Fri, 25 Sep 2009 12:05:20 +0000

Local Group
The Local Group (also called M31 group or the Andromeda group) is the group of galaxies that includes our galaxy, the Milky Way.
The group comprises over 30 galaxies, with its gravitational center located somewhere between the Milky Way and the Andromeda Galaxy..
Supergiant
Supergiants are the most massive stars.
Supergiants can have masses from 10 to 70 solar masses and brightness from 30,000 up to hundreds of thousands times the solar luminosity.
They vary greatly in radii, usually from 30 to 500, or even in excess of 1000 solar radii.
Because of their extreme masses they have short lifespans of only 10 to 50 million years and are only observed in young cosmic structures such as open clusters, the arms of spiral galaxies, and in irregular galaxies.
They are less abundant in spiral galaxy bulges, and are not observed in elliptical galaxies, or globular clusters, all of which are believed to be composed of old stars.
Currently, the largest known stars in terms of physical size, not mass or luminosity, are the supergiants VV Cephei, V354 Cephei, KW Sagitarii, KY Cygni, and the Garnet Star..
Barred spiral galaxy
A barred spiral galaxy is a spiral galaxy with a band of bright stars emerging from the center and running across the middle of the galaxy..
Magellanic Clouds
The two Magellanic Clouds are irregular dwarf galaxies orbiting our Milky Way galaxy, and thus are members of our Local Group of galaxies.The Large Magellanic Cloud (LMC) and its neighbour and relative, the Small Magellanic Cloud (SMC) are conspicuous objects in the southern hemisphere, looking like separated pieces of the Milky Way to the naked eye.
Observation, and theoretical evidence suggests that the LMC and SMC have been greatly distorted by tidal interaction with the Milky Way as they orbit around it; streams of neutral hydrogen connect them to the Milky Way and to each other, and both resemble disrupted barred spiral galaxies.
However, their gravity has affected our Galaxy as well, distorting the outer parts of the galactic disk..

“This article is brought to you by Gus Woltmann”.

Extrasolar Planets

admin — Fri, 25 Sep 2009 12:03:15 +0000

Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter.
Gas giants may have a rocky or metallic core—in fact, such a core is thought to be required for a gas giant to form—but the majority of its mass is in the form of the gases hydrogen and helium, with traces of water, methane, ammonia, and other hydrogen compounds.
Unlike rocky planets, which have a clearly defined difference between atmosphere and surface, gas giants do not have a well-defined surface; their atmospheres simply become gradually denser toward the core, perhaps with liquid or liquid-like states in between.
One cannot “land on” such planets in the traditional sense.
There are four gas giants in our solar system: Jupiter, Saturn, Uranus, and Neptune..
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet beyond the Solar System.
As of 11 November 2006, 209 extrasolar planets have been discovered. Known exoplanets are members of planetary systems that orbit a star.
There have also been unconfirmed reports of free-floating planetary-mass objects (that is, ones that do not orbit any star).
For centuries, extrasolar planets were a subject of speculation.
Astronomers generally supposed that some existed, but it was a mystery how common they were and how similar they were to the planets of the Solar System.
The first confirmed detections were finally made in the 1990s.
Since 2002, more than twenty have been discovered every year.
It is now estimated that at least 10% of sunlike stars have planets, and the true proportion may be much higher.
The discovery of extrasolar planets raises the question of whether some might support extraterrestrial life..
Red giant
A red giant is a large non-main sequence star of stellar classification K or M; so-named because of the reddish appearance of the cooler giant stars.
As Earth’s sun is of one solar mass, it is expected to become a red giant in about six billion years..
Astrobiology
Astrobiology is the study of life in space, combining aspects of astronomy, biology and geology.
It is focused primarily on the study of the origin, distribution and evolution of life..

“This article is brought to you by Gus Woltmann”.

Dark Matter

admin — Fri, 25 Sep 2009 12:01:19 +0000

Ultimate fate of the universe
The ultimate fate of the universe is a subject of study in the field of cosmology.
Vying scientific theories predict whether the life of the universe is finite or infinite.
Current understanding of matter in the universe suggests that the universe must consist of dark energy and dark matter to explain the current rate of expansion.
Mainstream models of the universe currently predict that the universe will go on expanding at an accelerating rate..
Big Bang nucleosynthesis
In physical cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang.
It is believed to be responsible for the formation of hydrogen (H-1 or simply H), its isotope deuterium (H-2 or D), the helium isotopes He-3 and He-4, and the lithium isotope Li-7.
Big Bang nucleosynthesis begins about one minute after the Big Bang, when the universe has cooled enough to form stable protons and neutrons, after baryogenesis.
From simple thermodynamical arguments, one can calculate the fraction of protons and neutrons based on the temperature at this point.
This fraction is in favour of protons, because the higher mass of the neutron results in a spontaneous decay of neutrons to protons with a half-life of about 15 minutes..
Shape of the Universe
The shape of the Universe is a subject of investigation within physical cosmology.
Cosmologists and astronomers describe the geometry of the Universe which includes both local geometry and global geometry.
The shape of the universe can be determined by measuring the average density of matter within it, assuming that all matter is evenly distributed, rather than the distortions caused by ‘dense’ objects such as galaxies.
This assumption is justified by the observations that, while the universe is “weakly” inhomogeneous and anisotropic (see the large-scale structure of the cosmos), it is on average homogeneous and isotropic.
Considerations of the geometry of the universe can be split into two parts; the local geometry relates to the observable universe, while the global geometry relates to the universe as a whole – including that which we can’t measure..
Dark matter
In astrophysics and cosmology, dark matter is hypothetical matter of unknown composition that does not emit or reflect enough electromagnetic radiation to be observed directly, but whose presence can be inferred from gravitational effects on visible matter.
According to present observations of structures larger than galaxy-sized as well as Big Bang cosmology, dark matter accounts for the vast majority of mass in the observable universe.
Fritz Zwicky used it for the first time to declare the observed phenomena consistent with dark matter observations as the rotational speeds of galaxies and orbital velocities of galaxies in clusters, gravitational lensing of background objects by galaxy clusters such as the Bullet cluster, and the temperature distribution of hot gas in galaxies and clusters of galaxies.
Dark matter also plays a central role in structure formation and galaxy evolution, and has measurable effects on the anisotropy of the cosmic microwave background.
All these lines of evidence suggest that galaxies, clusters of galaxies, and the universe as a whole contain far more matter than that which interacts with electromagnetic radiation: the remainder is called the “dark matter component.” The composition of dark matter is unknown, but may include ordinary and heavy neutrinos, recently postulated elementary particles such as WIMPs and axions, astronomical bodies such as dwarf stars and planets (collectively called MACHOs), and clouds of nonluminous gas.
Current evidence favors models in which the primary component of dark matter is new elementary particles, collectively called non-baryonic dark matter. The dark matter component has vastly more mass than the “visible” component of the universe.
At present, the density of ordinary baryons and radiation in the universe is estimated to be equivalent to about one hydrogen atom per cubic metre of space.
Only about 4% of the total energy density in the universe (as inferred from gravitational effects) can be seen directly.
About 22% is thought to be composed of dark matter.
The remaining 74% is thought to consist of dark energy, an even stranger component, distributed diffusely in space.
Some hard-to-detect baryonic matter makes a contribution to dark matter, but constitutes only a small portion.
Determining the nature of this missing mass is one of the most important problems in modern cosmology and particle physics..

“This article is brought to you by Gus Woltmann”.

Cosmic Rays

admin — Fri, 25 Sep 2009 11:59:17 +0000

Solar flare
A solar flare is a violent explosion in the Sun’s atmosphere with an energy equivalent to tens of millions of hydrogen bombs.
Solar flares take place in the solar corona and chromosphere, heating plasma to tens of millions of kelvins and accelerating the resulting electrons, protons and heavier ions to near the speed of light.
They produce electromagnetic radiation across the electromagnetic spectrum at all wavelengths from long-wave radio to the shortest wavelength gamma rays.
Most flares occur around sunspots, where intense magnetic fields emerge from the Sun’s surface into the corona.
The energy efficiency associated with solar flares may take several hours or even days to build up, but most flares take only a matter of minutes to release their energy..
Nucleosynthesis
Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons).
The primordial preexisting nucleons were formed from the quark-gluon plasma of the Big Bang as it cooled below ten million degrees.
This first process may be called nucleogenesis, the genesis of nucleons in the universe.
The subsequent nucleosynthesis of the elements (including all carbon, all oxygen, etc.) occurs primarily in stars either by nuclear fusion or nuclear fission..
Subatomic particle
A subatomic particle is a particle smaller than an atom: it may be elementary or composite.
Particle physics and nuclear physics concern themselves with the study of these particles, their interactions, and matter made up of them which do not aggregate into atoms. These particles include atomic constituents such as electrons, protons, and neutrons (protons and neutrons are actually composite particles, made up of quarks), as well as other particles such as photons and neutrinos which are produced copiously in the sun.
However, most of the particles that have been discovered and studied are not encountered under normal earth conditions; they are produced in cosmic rays and during scattering processes in particle accelerators..
Compton Gamma Ray Observatory
The Compton Gamma Ray Observatory (CGRO) was the second of the NASA “Great Observatories” to be launched to space, following the Hubble Space Telescope.
The observatory was launched on the Space Shuttle Atlantis, mission STS-37, on 5 April 1991.
It was deployed in low earth orbit at 450 km in order to avoid the Van Allen radiation belt.
It was the heaviest astrophysical payload ever flown at that time, at 17000 kg. The CGRO is part of NASA’s Great Observatories series, with the Hubble Space Telescope, the Chandra X-ray Observatory, and the Spitzer Space Telescope..

“This article is brought to you by Gus Woltmann”.

Black Holes

admin — Fri, 25 Sep 2009 11:57:25 +0000

Black hole
A black hole is a concentration of mass great enough that the force of gravity prevents anything from escaping it except through quantum tunnelling behaviour (known as Hawking Radiation).
The gravitational field is so strong that the escape velocity near it exceeds the speed of light.
This implies that nothing, not even light, can escape its gravity.
This makes this object invisible to the rest of the universe, hence the word “black”..
Quasar
A quasar is an astronomical source of electromagnetic energy, including light, which shows a very high redshift.
The scientific consensus is that this high redshift is the result of Hubble’s law.
This implies that quasars are very distant.
To be observable at that distance, the energy output of quasars must dwarf that of almost every known astrophysical phenomenon with the exception of comparatively short-lived supernovae and gamma-ray bursts.
They may readily release energy in levels equal to the output of hundreds of average galaxies combined.
The output of light is equivalent to one trillion suns.
Quasars are believed to be powered by accretion of material onto supermassive black holes in the nuclei of distant galaxies, making these luminous versions of the general class of objects known as active galaxies.
No other currently known mechanism appears able to explain the vast energy output and rapid variability..
Astrophysics
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties (luminosity, density, temperature and chemical composition) of astronomical objects such as stars, galaxies, and the interstellar medium, as well as their interactions..
Chandra X-ray Observatory
Chandra X-ray Observatory is a satellite launched on STS-93 by NASA on July 23, 1999.
It was named in honor of Indian-American physicist Subrahmanyan Chandrasekhar who is known for determining the mass limit for white dwarf stars to become neutron stars..

“This article is brought to you by Gus Woltmann”.

Astronomy

admin — Fri, 25 Sep 2009 11:55:28 +0000

Astrophysics
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties (luminosity, density, temperature and chemical composition) of astronomical objects such as stars, galaxies, and the interstellar medium, as well as their interactions..
Space observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects.
A large number of observatories have been launched into orbit, and most of them have greatly enhanced our knowledge of the cosmos.
Performing astronomy from the Earth’s surface is limited by the filtering and distortion of electromagnetic radiation due to the Earth’s atmosphere.
This makes it desirable to place astrononomical observation devices into space.
As a telescope orbits the Earth outside the atmosphere it is subject neither to twinkling (distortion due to thermal turbulences of the air) nor to light pollution from artificial light sources on the Earth.
But space-based astronomy is even more important for frequency ranges which are outside of the optic window and the radio window, the only two wavelength ranges of the electromagnetic spectrum that are not severely attenuated by the atmosphere.
For example, X-ray astronomy is nearly impossible when done from the Earth, and has reached its current important stand within astronomy only due to orbiting satellites with X-ray telescopes such as the Chandra observatory or XMM-Newton observatory.
Infrared and ultraviolet are also greatly blocked..
Supergiant
Supergiants are the most massive stars.
Supergiants can have masses from 10 to 70 solar masses and brightness from 30,000 up to hundreds of thousands times the solar luminosity.
They vary greatly in radii, usually from 30 to 500, or even in excess of 1000 solar radii.
Because of their extreme masses they have short lifespans of only 10 to 50 million years and are only observed in young cosmic structures such as open clusters, the arms of spiral galaxies, and in irregular galaxies.
They are less abundant in spiral galaxy bulges, and are not observed in elliptical galaxies, or globular clusters, all of which are believed to be composed of old stars.
Currently, the largest known stars in terms of physical size, not mass or luminosity, are the supergiants VV Cephei, V354 Cephei, KW Sagitarii, KY Cygni, and the Garnet Star..
Spitzer space telescope
Spitzer Space Telescope (formerly the Space Infrared Telescope Facility [SIRTF]) is an infrared space observatory, the fourth and final of NASA’s Great Observatories.
The first images taken by SST were designed to show off the abilities of the telescope and showed a glowing stellar nursery; a swirling, dusty galaxy; a disc of planet-forming debris; and organic material in the distant universe.
In March of 2006, astronomers reported an 80 light year-long nebula near the center of the Milky Way Galaxy, the Double Helix Nebula, which is, as the name implies, twisted into a double spiral shape.
This is thought to be evidence of massive magnetic fields generated by the gas disc orbiting the supermassive black hole at the galaxy’s center, 300 light years from the nebula and 25,000 light years from Earth.
This nebula was discovered by the Spitzer Space Telescope..