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
Ecosystem, vegetation affect intensity of urban heat island effect
Space & Earth / Earth Sciences
12 hours ago |
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NASA researchers studying urban landscapes have found that the intensity of the "heat island" created by a city depends on the ecosystem it replaced and on the regional climate. Urban areas developed in arid and semi-arid ...
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NASA unveils latest results from lunar mission
Space & Earth / Space Exploration
11 hours ago |
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NASA's current mission in orbit around the moon, the Lunar Reconnaissance Orbiter, or LRO, has been providing crucial insights about our nearest celestial neighbor since its launch in June. At a scientific ...
Rare earth metal enhances phosphate glass
19 hours ago |
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(PhysOrg.com) -- Adding cerium oxide to phosphate glass rather than the commonly used silicate glass may make glasses that block ultraviolet light and have increased radiation damage resistance while remaining colorless, ...
Icy moons of Saturn and Jupiter may have conditions needed for life
12 hours ago |
4.8 / 5 (13) |
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(PhysOrg.com) -- Scientists once thought that life could originate only within a solar system's "habitable zone," where a planet would be neither too hot nor too cold for liquid water to exist on its surface. ...
A unique geography -- and soot and dust -- conspire against Himalayan glaciers
Space & Earth / Earth Sciences
23 hours ago |
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"So many disparate elements, both natural and man-made, converge in the Himalayas," said William Lau, a climatologist from NASA's Goddard Space Flight Center in Greenbelt, Md. "There's no other place in the ...
Close-up photos of dying star show our sun's fate (w/ Video)
18 hours ago |
4.9 / 5 (16) |
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(PhysOrg.com) -- About 550 light-years from Earth, a star like our Sun is writhing in its death throes. Chi Cygni has swollen in size to become a red giant star so large that it would swallow every planet ...
MESSENGER team releases first global map of mercury
Space & Earth / Space Exploration
14 hours ago |
5 / 5 (5) |
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(PhysOrg.com) -- NASA's MESSENGER mission team and cartographic experts from the U. S. Geological Survey have created a critical tool for planning the first orbital observations of the planet Mercury - a global ...
New results from a terra-ific decade in orbit
Space & Earth / Earth Sciences
14 hours ago |
5 / 5 (1) |
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December 18, 2009, marks the tenth year since the launch of Terra, one of NASA's "flagship" Earth observing satellites. But the decade is more than just a mechanical milestone. With each additional day and ...
Miracle light: Can lasers solve the energy crisis?
12 hours ago |
4.6 / 5 (9) |
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Next year will mark the 50th birthday of the laser, one of the most productive and widely used mega-inventions of the last century. Scientists hope that 2010 also will see the launch of laser technology's greatest challenge: ...
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