Portal:Solar System
The Solar System Portal
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. It formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc. The Sun is a typical star that maintains a balanced equilibrium by the fusion of hydrogen into helium at its core, releasing this energy from its outer photosphere. Astronomers classify it as a G-type main-sequence star.
The largest objects that orbit the Sun are the eight planets. In order from the Sun, they are four terrestrial planets (Mercury, Venus, Earth and Mars); two gas giants (Jupiter and Saturn); and two ice giants (Uranus and Neptune). All terrestrial planets have solid surfaces. Inversely, all giant planets do not have a definite surface, as they are mainly composed of gases and liquids. Over 99.86% of the Solar System's mass is in the Sun and nearly 90% of the remaining mass is in Jupiter and Saturn.
There is a strong consensus among astronomers that the Solar System has at least nine dwarf planets: Ceres, Orcus, Pluto, Haumea, Quaoar, Makemake, Gonggong, Eris, and Sedna. There are a vast number of small Solar System bodies, such as asteroids, comets, centaurs, meteoroids, and interplanetary dust clouds. Some of these bodies are in the asteroid belt (between Mars's and Jupiter's orbit) and the Kuiper belt (just outside Neptune's orbit). Six planets, seven dwarf planets, and other bodies have orbiting natural satellites, which are commonly called 'moons'.
The Solar System is constantly flooded by the Sun's charged particles, the solar wind, forming the heliosphere. Around 75–90 astronomical units from the Sun, the solar wind is halted, resulting in the heliopause. This is the boundary of the Solar System to interstellar space. The outermost region of the Solar System is the theorized Oort cloud, the source for long-period comets, extending to a radius of 2,000–200,000 AU. The closest star to the Solar System, Proxima Centauri, is 4.25 light-years (269,000 AU) away. Both stars belong to the Milky Way galaxy. (Full article...)
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Internally, Venus has a core, mantle, and crust. Venus lacks an internal dynamo, and its weakly induced magnetosphere is caused by atmospheric interactions with the solar wind. Internal heat escapes through active volcanism, resulting in resurfacing instead of plate tectonics. Venus is one of two planets in the Solar System, the other being Mercury, that have no moons. Conditions perhaps favourable for life on Venus have been identified at its cloud layers. Venus may have had liquid surface water early in its history with a habitable environment, before a runaway greenhouse effect evaporated any water and turned Venus into its present state. (Full article...)
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General images
The following are images from various Solar System-related articles on Wikipedia.
Did you know –
- ...that the passing of the Great Comet of 1577 (pictured) caused almost century-long debate, during which Galileo argued that comets were merely optical illusions?
- ...that systematic mapping of the Michelangelo quadrangle on Mercury has revealed the presence of four nearly obliterated multi-ring impact basins, possibly the oldest features in the mapped areas of the planet?
- ...that there have been several proposals for space advertising projects, including a giant, 1km² billboard visible from Earth?
- ...that some astrologers claim Earth has a second moon they call Lilith?
- ...that ridges and escarpments in the Victoria quadrangle of the planet Mercury have been associated with the stresses caused by the Sun slowing Mercury's rotation through tidal forces?
- ...that J002E3 was at first thought to be a new moon of Earth when discovered in 2002 but was later found to be the third stage of the Apollo 12 Saturn V?
- ...that the Tooting impact crater on Mars was named after the London suburb of the same name because the discoverer "thought [his] mum and brother would get a kick out of having their home town paired with a land form on Mars"?
- ...that 99% of the mass of the Carme group, a group of retrograde irregular satellites of Jupiter, is located in Carme?
Categories
Solar System | ||
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Celestial mechanics | Comets | ...in fiction |
Minor planets | Moons | Planetary missions |
Planets... | Sun | Surface feature nomenclature... |
In the news
- April 7: NASA's helicopter Ingenuity survives its first night at Mars
- December 25: 'Earth-based life can survive in hydrogen-rich atmospheres': MIT professor Dr Seager tells Wikinews about her research on organisms thriving in oxygen-less environment
- July 7: Astronomer Anthony Boccaletti discusses observation of birth of potential exoplanet with Wikinews
- May 31: SpaceX successfully launches its first crewed spaceflight
- May 22: Astronomer tells Wikinews about discovery of closest black hole known so far
- October 12: Cosmonaut Alexei Leonov dies at age 85
- October 10: Swedish academy announces 2019 Nobel Prize winners in physics
- September 14: Astronomers find water vapour in atmosphere of exoplanet K2-18b
- March 5: SpaceX Crew Dragon capsule docks with International Space Station
- January 9: Simple animals could live in Martian brines: Wikinews interviews planetary scientist Vlada Stamenković
- November 29: NASA's InSight Lander makes it to Mars
- October 12: Manned Soyuz space mission aborts during launch
Major topics
Solar System: Planets (Definition · Planetary habitability · Terrestrial planets · Gas giants · Rings) · Dwarf planets (Plutoid) · Colonization · Discovery timelineˑ Exploration · Moons · Planetariums
- Sun: Sunspot · Solar wind · Solar flare · Solar eclipse
- Mercury: Geology · Exploration (Mariner 10 · MESSENGER · BepiColombo) · Transit
- Venus: Geology · Atmosphere · Exploration (Venera · Mariner program 2/5/10 · Pioneer · Vega 1/2ˑ Magellan · Venus Express) · Transit
- Earth: History · Geology · Geography · Atmosphere · Rotation
- Moon: Geology · Selenography · Atmosphere · Exploration (Luna · Apollo 8/11) · Orbit · Lunar eclipse
- Mars: Moons (Phobos · Deimos) · Geology · Geography · Atmosphere · Exploration (Mariner · Mars · Viking 1/2 · Pathfinder · MER)
- Ceres: Exploration (Dawn)
- Jupiter: Moons (Amalthea, Io · Europa · Ganymede · Callisto) · Rings · Atmosphere · Magnetosphere · Exploration (Pioneer 10/11 · Voyager 1/2 · Ulysses · Cassini · Galileo · New Horizons)
- Saturn: Moons (Mimas · Enceladus · Tethys · Dione · Rhea · Titan · Iapetus) · Rings · Exploration (Pioneer 11 · Voyager 1/2 · Cassini–Huygens)
- Uranus: Moons (Miranda · Ariel · Umbriel · Titania · Oberon) · Rings · Exploration (Voyager 2)
- Neptune: Moons (Triton) · Rings · Exploration (Voyager 2)
- Planets beyond Neptune
- Pluto: Moons (Charon, Nix, Hydra, Kerberos, Styx) · Geology · Atmosphere · Exploration (New Horizons)
- Haumea: Moons (Hi'iaka, Namaka) · Ring
- Quaoar: Weywot · Rings
- Makemake: S/2015 (136472) 1
- Gonggong: Xiangliu
- Eris: Dysnomia
- Sedna
- Small bodies: Meteoroids · Asteroids (Asteroid belt) · Centaurs · TNOs (Kuiper belt · Scattered disc · Oort cloud) · Comets (Hale–Bopp · Halley's · Hyakutake · Shoemaker–Levy 9)
- Formation and evolution of the Solar System: History of Solar System formation and evolution hypotheses · Nebular hypothesis
- See also: Featured content · Featured topic · Good articles · List of objects
Bold articles are featured.
Italicized articles are on dwarf planets or major moons.
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