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
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 |
4.8 / 5 (19) |
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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 |
4.8 / 5 (11) |
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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.
Building Planet Earth
Oct 22, 2009 |
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A new study shows how rocky planets are formed from the manic swirl of gas and dust that surround a young star, and determines what chemical building blocks are used to construct the planets. Understanding ...
Last visit home for ESA's comet chaser Rosetta
Space & Earth / Space Exploration
Oct 20, 2009 |
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ESA's Rosetta comet chaser will swing by Earth on 13 November to pick up orbital energy and begin the final leg of its 10-year journey to the outer Solar System. Several observations of the Earth-Moon system ...
Galileo's Jupiter Journey Began Two Decades Ago
Space & Earth / Space Exploration
Oct 19, 2009 |
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(PhysOrg.com) -- NASA's Galileo spacecraft began what would become a 14-year odyssey of exploration 20 years ago this Sunday, Oct. 18. Galileo was humanity's first emissary to orbit a planet in the outer solar ...
Meteorite from Sept. 25 fireball event recovered and presented
Space & Earth / Space Exploration
Oct 16, 2009 |
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When Tony Garchinski heard a loud crash just after 9 p.m. on Friday, September 25 he didn't think much of it. That is, until he awoke the next morning to find the windshield of his mom's Nissan Pathfinder ...
Scientists Explore Galactic Frontier, Release First-Ever All-Sky Map (w/ Video)
Space & Earth / Space Exploration
Oct 15, 2009 |
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(PhysOrg.com) -- NASA's Interstellar Boundary Explorer, or IBEX, spacecraft has made it possible for scientists to construct the first comprehensive sky map of our solar system and its location in the Milky ...
How the Moon produces its own water
Space & Earth / Space Exploration
Oct 15, 2009 |
4.7 / 5 (14) |
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(PhysOrg.com) -- The Moon is a big sponge that absorbs electrically charged particles given out by the Sun. These particles interact with the oxygen present in some dust grains on the lunar surface, producing ...
Researcher hunts for new planets, seeking clues on solar system's origin
Oct 13, 2009 |
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(PhysOrg.com) -- The Cornell assistant professor of astronomy works on instrumentation that searches the night skies for planets outside our solar system, called extrasolar planets.
Islands of Life Across Space and Time
Space & Earth / Space Exploration
Oct 06, 2009 |
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A new study by the University of Puerto Rico at Arecibo shows the first quantitative evaluation of planetary habitability. The study identifies some potential habitats in the solar system and also shows how ...
