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
First fuzzy photos of planets outside solar system
Nov 13, 2008 |
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(PhysOrg.com) -- Astronomers using the Gemini North telescope and W.M. Keck Observatory on Hawaii's Mauna Kea have obtained the first-ever direct images identifying a multi-planet system around a normal star. ...
Critical turning point can trigger abrupt climate change
Space & Earth / Earth Sciences
Apr 20, 2009 |
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Ice ages are the greatest natural climate changes in recent geological times. Their rise and fall are caused by slight changes in the Earth's orbit around the Sun due to the influence of the other planets. But we do not know ...
Ulysses spacecraft data indicate Solar System shield lowering
Space & Earth / Space Exploration
Sep 23, 2008 |
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(PhysOrg.com) -- Data from the joint ESA/NASA Ulysses mission show that the Sun has reduced its output of solar wind to the lowest levels since accurate readings have become available. This current state of ...
New computer simulations show how special the solar system is
Aug 07, 2008 |
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Prevailing theoretical models attempting to explain the formation of the solar system have assumed it to be average in every way. Now a new study by Northwestern University astronomers, using recent data from the 300 exoplanets ...
Theory of the sun's role in formation of the solar system questioned
Space & Earth / Space Exploration
Sep 04, 2008 |
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A strange mix of oxygen found in a stony meteorite that exploded over Pueblito de Allende, Mexico nearly 40 years ago has puzzled scientists ever since. Small flecks of minerals lodged in the stone and thought ...
Solar System's Young Twin Has Two Asteroid Belts
Oct 27, 2008 |
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(PhysOrg.com) -- Astronomers have discovered that the nearby star Epsilon Eridani has two rocky asteroid belts and an outer icy ring, making it a triple-ring system. The inner asteroid belt is a virtual twin ...
First picture of likely planet around sun-like star unveiled
Sep 16, 2008 |
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(PhysOrg.com) -- University of Toronto astronomers have unveiled what is likely the first picture of a planet around a star similar to the sun.
LCROSS Impact Finds Water on the Moon
Space & Earth / Space Exploration
Nov 13, 2009 |
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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 ...
Los Alamos observatory fingers cosmic ray 'hot spots'
Nov 24, 2008 |
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A Los Alamos National Laboratory cosmic-ray observatory has seen for the first time two distinct hot spots that appear to be bombarding Earth with an excess of cosmic rays. The research calls into question ...
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.
Gravitational Space Corridors Could Slash Space Travel Costs (w/ Video)
Space & Earth / Space Exploration
Sep 16, 2009 |
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(PhysOrg.com) -- Scientists studying space travel possibilities have proposed that gravitational space corridors could be used by spacecraft, in much the same way as ships use ocean currents. Taking advantage ...
NASA Spacecraft Reveal Largest Crater in Solar System
Space & Earth / Space Exploration
Jun 26, 2008 |
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New analysis of Mars' terrain using NASA spacecraft observations reveals what appears to be by far the largest impact crater ever found in the solar system
The Stars My Destination
Space & Earth / Space Exploration
Nov 10, 2009 |
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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 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 ...
Discovery of the source of the most common meteorites
Jul 10, 2008 |
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Astronomy & Astrophysics is publishing the first discovery by T. Mothé-Diniz (Brazil) and D. Nesvorný (USA) of asteroids with a spectrum similar to that of ordinary chondrites, the meteoritic material that m ...
