Portal:Solar System
The Solar System Portal

The Solar System is the gravitationally bound system of the Sun and the masses that orbit it, most prominently its eight planets, of which Earth is one. The Solar System is an isolated single-star planetary system (not part of a larger star system) within the Milky Way Galaxy. The system formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, creating the Sun and a protoplanetary disc from which the orbiting bodies assembled.
The Sun accounts for 99.86% of the Solar System's total mass. Inside the Sun's core, hydrogen is fused into helium, releasing energy that is emitted through the Sun's photosphere. This creates the heliosphere and a decreasing temperature gradient across the Solar System.
The next most massive objects of the system are the eight planets, which by definition dominate the orbits they occupy. Closest to the Sun in order of increasing distance are the terrestrial planets – Mercury, Venus, Earth and Mars. These four planets are part of the inner Solar System. Earth and Mars are the only planets that orbit within the Sun's habitable zone, in which sunlight can keep surface water liquid under atmospheric pressure. Beyond the frost line at about five astronomical units (AU), are the planets of the outer Solar System: two gas giants (Jupiter and Saturn) and two ice giants (Uranus and Neptune). Jupiter and Saturn possess nearly 90% of the non-stellar mass of the Solar System.
Objects of planetary mass that do not dominate their orbit but directly orbit the Sun are called dwarf planets. The International Astronomical Union's Minor Planet Center lists Ceres, Pluto, Eris, Makemake, and Haumea as dwarf planets. Four other Solar System objects are generally identified as such: Orcus, Quaoar, Gonggong, and Sedna. Less massive than the dwarf planets are the vast number of small Solar System bodies, such as asteroids, comets, centaurs, meteoroids, and interplanetary dust clouds. The dwarf planet Ceres and many of these smaller bodies are located in the asteroid belt (between Mars's and Jupiter's orbit), while all other dwarf planets are members of populations of trans-Neptunian objects, which may be found in the Kuiper belt just outside Neptune or in the further scattered disc. (Full article...)
Selected article –
The Sun orbits the Galactic Center at a distance of 24,000 to 28,000 light-years. Its mean distance from Earth is about 1.496×108 kilometres or about 8 light-minutes. The distance between the Sun and the Earth was used to define a unit of length called the astronomical unit (au), now defined to be 149.5978707×106 kilometres. It is the largest and most massive object in the Solar System; its diameter is about 1,391,400 km (864,600 mi), around 109 times that of Earth. The Sun's mass is around 330,000 times that of Earth, making up about 99.86% of the total mass of the Solar System. The mass of the Sun's surface layer, its photosphere, consists mostly of hydrogen (~73%) and helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron. (Full article...)
Selected picture
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 the Caloris Basin on Mercury, one of the largest impact basins in the Solar System, is surrounded by a series of geological formations believed to have been produced by the basin's ejecta?
- ...that Kordylewski clouds are large concentrations of dust that orbit Earth at the distance of the Moon?
- ...that no viable solution has yet been found to counteract radiation from space, which is a serious threat to astronauts on any future mission to Mars?
- ...that Claudia Alexander was the last project manager of NASA's Galileo mission to Jupiter?
Categories
| Solar System | ||
|---|---|---|
| Celestial mechanics | Comets | ...in fiction |
| Minor planets | Moons | Planetary missions |
| Planets... | Sun | Surface feature nomenclature... |

Solar System news
- 26 July 2026 – International Space Station expeditions
- Expedition 74, the joint NASA–Roscosmos–ESA expedition aboard the International Space Station, ends after the Soyuz MS-28 undocks and lands on Earth in Kazakhstan. (CNN)
- 16 July 2026 –
- Astronomers report the first observationally confirmed atmosphere around a rocky exoplanet within its star's habitable zone, after detecting helium escaping from the upper atmosphere of LHS 1140 b, a super-Earth approximately 49 light-years from Earth. (Space.com)
- 15 July 2026 – Discoveries of exoplanets
- Astronomers directly image the exoplanet Beta Pictoris d next to its star, located 63 light-years away, using NASA's James Webb Space Telescope and European Southern Observatory's Very Large Telescope. It is also reported to be fainter than its sibling Beta Pictoris b. The discovery is published in the The Astrophysical Journal. (ABC News) (Space.com)
- 16 June 2026 – Discoveries of exoplanets
- The NASA's James Webb Space Telescope discovers that the Hot Jupiter exoplanet HD 80606 b is being roasted by its home star. The research findings were presented at the 248th American Astronomical Society in Pasedena, California, U.S. (Space.com)
- 9 June 2026 – Artemis program
- NASA announces that its astronauts Randy Bresnik, Frank Rubio, and Andre Douglas, and ESA astronaut Luca Parmitano will crew the Artemis III mission in late 2027. The mission's goal is to evaluate rendezvous and docking operations with SpaceX's Starship HLS and Blue Origin's Blue Moon spacecraft. (NBC News)
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.
Things you can do

|
|
Here are some tasks awaiting attention:
|
Related portals
Related WikiProjects
Associated Wikimedia
The following Wikimedia Foundation sister projects provide more on this subject:
-
Commons
Free media repository -
Wikidata
Free knowledge base -
Wikiquote
Collection of quotations -
Wikisource
Free-content library -
Wikiversity
Free learning tools -
Wiktionary
Dictionary and thesaurus










