Solar System
hideThe Solar System[a] consists of the Sun and those celestial objects bound to it by gravity, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The Sun's retinue of objects circle it in a nearly flat disc called the ecliptic plane, most of the mass of which is contained within eight relatively solitary planets whose orbits are almost circular. The four smaller inner planets; Mercury, Venus, Earth and Mars, also called the terrestrial planets, are primarily composed of rock and metal. The four outer planets, Jupiter, Saturn, Uranus and Neptune, also called the gas giants, are composed largely of hydrogen and helium and are far more massive than the terrestrials.
The Solar System is also home to two main belts of small bodies. The asteroid belt, which lies between Mars and Jupiter, is similar to the terrestrial planets as it is composed mainly of rock and metal. The Kuiper belt (and its subpopulation, the scattered disc), which lies beyond Neptune's orbit, is composed mostly of ices such as water, ammonia and methane. Within these belts, five individual objects, Ceres, Pluto, Haumea, Makemake and Eris, are recognised to be large enough to have been rounded by their own gravity, and are thus termed dwarf planets. The hypothetical Oort cloud, which acts as the source for long-period comets, may also exist at a distance roughly a thousand times beyond these regions.
Within the Solar System, various populations of small bodies, such as comets, centaurs and interplanetary dust, freely travel between these regions, while the solar wind, a flow of plasma from the Sun, creates a bubble in the interstellar medium known as the heliosphere, which extends out to the edge of the scattered disc.
Six of the planets and three of the dwarf planets are orbited by natural satellites, usually termed "moons" after Earth's Moon. Each of the outer planets is encircled by planetary rings of dust and other particles.
For more information about Solar System, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with solar system
SOFIA Seeks Secrets of Planetary Birth
Space & Earth / Space Exploration
Nov 19, 2009 |
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You don't always have to have a rocket to do rocket science. Sometimes a mere airplane will do - that is, a mere Boeing 747 toting a 17-ton, 9-foot wide telescope named SOFIA.
Dawn Enters Asteroid Belt -- For Good
Space & Earth / Space Exploration
Nov 16, 2009 |
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(PhysOrg.com) -- NASA's Dawn spacecraft re-entered our solar system's asteroid belt today, Nov. 13, and this time it will stay there.
LCROSS Impact Finds Water on the Moon
Space & Earth / Space Exploration
Nov 13, 2009 |
4.9 / 5 (31) |
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(PhysOrg.com) -- The argument that the moon is a dry, desolate place no longer holds water. Secrets the moon has been holding, for perhaps billions of years, are now being revealed to the delight of scientists ...
Research gives new insights into 4 billion year-old meteorites
Nov 12, 2009 |
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(PhysOrg.com) -- Scientists have gained new insight into the makeup of ancient meteorites called Carbonaceous Chondrites, in research published in the October edition of the journal Earth Science and Planetary Le ...
A faraway planet intrigues: Exoplanet with extremely tilted orbit raises new interest in stellar astronomy
Nov 12, 2009 |
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(PhysOrg.com) -- Two teams of astronomers have found a planet outside the solar system that might be orbiting backwards compared to its star's rotation, a discovery that could shed light on how unique the ...
Atomic Particles Help Solve Planetary Puzzle
Space & Earth / Earth Sciences
Nov 10, 2009 |
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(PhysOrg.com) -- A University of Arkansas professor and his colleagues have shown that the Earth's mantle contains the same isotopic signatures from magnesium as meteorites do, suggesting that the planet formed ...
The 2009 Leonid Meteor Shower
Space & Earth / Space Exploration
Nov 10, 2009 |
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This year's Leonid meteor shower peaks on Tuesday, Nov. 17th. If forecasters are correct, the shower should produce a mild but pretty sprinkling of meteors over North America followed by a more intense outburst ...
The Stars My Destination
Space & Earth / Space Exploration
Nov 10, 2009 |
4.8 / 5 (23) |
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The Voyager spacecraft are now in the outermost layer of the heliosphere, traveling toward interstellar space - the first man-made spacecraft to travel such a vast distance from Earth.
Scientists Reproduce a Building Block of Life in Laboratory
Nov 06, 2009 |
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(PhysOrg.com) -- NASA scientists studying the origin of life have reproduced uracil, a key component of our hereditary material, in the laboratory.
Unusual meteorite found by time-lapse camera observatory
Space & Earth / Space Exploration
Nov 05, 2009 |
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(PhysOrg.com) -- An unusual meteorite with an interesting orbit has been tracked to the ground using a photographic observatory that records time-lapse images of fireballs traveling across the sky.
Rosetta's final Earth boost
Space & Earth / Space Exploration
Nov 04, 2009 |
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ESA's comet chaser Rosetta will swing by Earth for the last time on 13 November to pick up energy and begin the final leg of its 10-year journey to comet 67P/Churyumov-Gerasimenko. ESA's European Space Operations ...
Fantastic Voyage
Space & Earth / Space Exploration
Nov 02, 2009 |
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By travelling to the outer solar system, the two Voyager spacecraft allowed us to see amazing details of far-distant planets and moons.
'Ultra-primitive' particles found in comet dust
Space & Earth / Space Exploration
Nov 02, 2009 |
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Dust samples collected by high-flying aircraft in the upper atmosphere have yielded an unexpectedly rich trove of relicts from the ancient cosmos, report scientists from the Carnegie Institution. The stratospheric ...
Icebreaker: Scientist brings out big gun to explore behavior of ice in planetary collisions
Space & Earth / Space Exploration
Oct 29, 2009 |
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(PhysOrg.com) -- Every month, Sarah Stewart-Mukhopadhyay fires her 20-foot gun in the basement of Harvard's Hoffman Lab, sending shivers through the concrete and steel structure that can be picked up by seismometers ...
Detecting Life-Friendly Moons
Space & Earth / Space Exploration
Oct 26, 2009 |
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The search for life-friendly real estate around distant stars doesn't have to be limited to planets. New research shows that habitable exomoons can be detected with a new method using current technology.
