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The Solar System Portal
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. It was formed 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc. The Sun is an ordinary main sequence star that maintains a balanced equilibrium by the fusion of hydrogen into helium at its core, releasing this energy from its outer photosphere.
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 eight dwarf planets: Ceres, 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, six 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, 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 2,000–200,000 astronomical units (0.032–3.2 light-years). The closest star to the Solar System, Proxima Centauri, is 4.25 light-years away. Both stars belong to the Milky Way galaxy. ( Full article...)
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Makemake as seen by the Hubble Space Telescope.
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These images are composites of the complete radar image collection obtained by the Magellan mission. The Magellan spacecraft was launched aboard Space Shuttle Atlantis in May 1989 and began mapping the surface of Venus in September 1990. The spacecraft continued to orbit Venus for four years, returning high-resolution images, altimetry, thermal emissions and gravity maps of 98 percent of the surface. Magellan spacecraft operations ended on October 12, 1994, when the radio contact was lost with the spacecraft during its controlled descent into the deeper portions of the Venusian atmosphere. -
Solar eclipse of 11 August 1999 The solar eclipse of 1999 August 11, as seen from France. This was the most viewed total eclipse in human history, although some areas offered impaired visibility due to adverse weather conditions. The path of the Moon's shadow began in the Atlantic Ocean, before traversing Cornwall, northern France, southern Germany, Austria, Hungary and northern Serbia. Its maximum was in Romania, and it continued across the Black Sea, Turkey, Iran, southern Pakistan and India. -
Photo credit: Joaquim Alves GasparIllustration of the Ptolemaic geocentric model of the Universe (the theory that the Earth is the center of the universe) by Portuguese cosmographer and cartographer Bartolomeu Velho. Taken from his treatise Cosmographia, made in Paris, 1568. Notice the distances of the bodies to the centre of the Earth (left) and the times of revolution, in years (right). -
Image credit: Cassini orbiterThe most detailed full-disc view of Titan, the largest moon of Saturn and second-largest in the Solar System. The brighter region on the right side and equatorial region is named Xanadu, and the large, dark region at the center is Shangri-la. This image has been processed to reduce the effects of the atmosphere and to sharpen surface features. It has been trimmed to show only the illuminated surface and not the atmosphere above the edge of the moon. -
Image credit: SeavAn animated image showing the apparent retrograde motion of Mars in 2003 as seen from Earth. All the true planets appear to periodically switch direction as they cross the sky. Because Earth completes its orbit in a shorter period of time than the planets outside its orbit, we periodically overtake them, like a faster car on a multi-lane highway. When this occurs, the planet will first appear to stop its eastward drift, and then drift back toward the west. Then, as Earth swings past the planet in its orbit, it appears to resume its normal motion west to east. -
Mars, the fourth planet from the Sun, is named after the Roman god of war because of its blood red color. Mars has two small, oddly-shaped moons, Phobos and Deimos, named after the sons of the Greek god Ares. At some point in the future Phobos will be broken up by gravitational forces. The atmosphere on Mars is 95% carbon dioxide. In 2003 methane was also discovered in the atmosphere. Since methane is an unstable gas, this indicates that there must be (or have been within the last few hundred years) a source of the gas on the planet.
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Photograph credit: European Space AgencyMars is the fourth planet from the Sun and is known as the "Red Planet" due to its reddish appearance as seen from Earth. The planet is named after Mars, the Roman god of war. A terrestrial planet, Mars has a thin atmosphere and surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts and polar ice caps of the Earth. The planet has the highest mountain in the Solar System, Olympus Mons, as well as the largest canyon, Valles Marineris. Mars's rotation period and seasonal cycles are also similar to those of the Earth. Of all the planets in the Solar System other than Earth, Mars is the most likely to harbour liquid water and perhaps life. There are ongoing investigations assessing Mars's past potential for habitability, as well as the possibility of extant life. Future astrobiology missions are planned, including NASA's Mars 2020 rover and the European Space Agency (ESA)'s Rosalind Franklin rover. In November 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region of the planet. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped.
This picture is a true-colour image of Mars, taken from a distance of about 240,000 kilometres (150,000 mi) by the OSIRIS instrument on ESA's Rosetta spacecraft, during its February 2007 flyby of the planet. The image was generated using OSIRIS's orange (red), green and blue filters. -
Photo credit: Voyager 1False-color detail of Jupiter's atmosphere, imaged by Voyager 1, showing the Great Red Spot and a passing white oval. The wavy cloud pattern to the left of the Red Spot is a region of extraordinarily complex and variable wave motion. To give a sense of Jupiter's scale, the white oval storm directly below the Great Red Spot is approximately the same diameter as Earth. -
A TRACE image of sunspots on the surface, or photosphere, of the Sun from September 2002, is taken in the far ultraviolet on a relatively quiet day for solar activity. However, the image still shows a large sunspot group visible as a bright area near the horizon. Although sunspots are relatively cool regions on the surface of the Sun, the bright glowing gas flowing around the sunspots have a temperature of over one million °C (1.8 million °F). The high temperatures are thought to be related to the rapidly changing magnetic field loops that channel solar plasma.
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The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, heated to incandescence by nuclear-fusion reactions in its core, radiating the energy mainly as visible light and infrared radiation. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometres (860,000 mi), or 109 times that of Earth. Its mass is about 330,000 times that of Earth, and accounts for about 99.86 percent of the total mass of the Solar System. Roughly three-quarters of the Sun's mass consists of hydrogen; the rest is mostly helium, with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron. This diagram illustrates the general structure of the Sun, with all features drawn to scale. -
Jupiter Credit: Cassini probeJupiter is the fifth planet from the Sun and by far the largest within the Solar System. It is 318 times more massive than Earth, with a diameter 11 times that of Earth, and with a volume 1300 times that of Earth. Its best known feature is the Great Red Spot, a storm larger than Earth, which was first observed by Galileo four centuries ago. This picture, taken by the Cassini orbiter was one of 26 thousand images taken of Jupiter during the course of its flyby and is the most detailed global color portrait of the planet ever produced. -
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Earthrise, as seen by Apollo 8 Credit: William AndersEarthrise, the first occasion in which humans saw the Earth seemingly rising above the surface of the Moon, taken during the Apollo 8 mission on December 24, 1968. This view was seen by the crew at the beginning of its fourth orbit around the Moon, although the first photograph taken was in black-and-white. Note that the Earth is in shadow here. A photo of a fully lit Earth would not be taken until the Apollo 17 mission. -
Image credit: United States Geological SurveyA composite image of Olympus Mons on Mars, the tallest known volcano and mountain in the Solar System. This image was created from black-and-white imagery from the USGS's Mars Global Digital Image Mosaic and color imagery acquired from the 1978 visit of Viking 1. -
Photo credit: The Apollo 17 crewThe Blue Marble is a famous photograph of Earth. NASA officially credits the image to the entire Apollo 17 crew — Eugene Cernan, Ronald Evans and Jack Schmitt — all of whom took photographic images during the mission. Apollo 17 passed over Africa during daylight hours and Antarctica is also illuminated. The photograph was taken approximately five hours after the spacecraft's launch, while en route to the Moon. Apollo 17, notably, was the last manned lunar mission; no humans since have been at a range where taking a "whole-Earth" photograph such as "The Blue Marble" would be possible. -
Photo credit: Cassini orbiterRhea, at 1,528 kilometres (949 mi) across, is the second-largest moon of Saturn and the ninth largest moon in the Solar System. It was discovered in 1672 by Giovanni Domenico Cassini, who named it after the Titan Rhea of Greek mythology, "mother of the gods".
The giant Tirawa impact basin is seen above and to the right of center. Tirawa, and another basin to its southwest, are both covered in impact craters, indicating they are quite ancient. -
Realistic-color mosaic of images of Jupiter's moon Europa taken by NASA's Jupiter orbiter Galileo in 1995 and 1998. This view of the moon's anti-Jovian hemisphere shows numerous lineae, linear features created via a tectonic process in which crustal plates of water ice floating on a subsurface ocean (kept warm by tidal flexing) shift in relative position. Reddish regions are areas where the ice has a higher mineral content. The north polar region is at right. ( Geologic features are annotated in Commons.) -
Photo credit: Cassini orbiterSaturn eclipsing the Sun, as seen by the Cassini orbiter. Individual rings seen in this image include (in order, starting from most distant): E ring, Pallene ring (visible very faintly in an arc just below Saturn), G ring, Janus/Epimetheus ring (faint), F ring (narrow brightest feature), Main rings (A,B,C), and D ring (bluish, nearest Saturn). Interior to the G ring and above the brighter main rings is the pale dot of Earth. -
Comet Hale-Bopp 29-03-1997 Credit: Philipp SalzgeberComet Hale–Bopp sails across the sky in the vicinity of Pazin in Istria, Croatia. To the lower right of the comet the Andromeda Galaxy is also faintly visible. The comet was visible to the naked eye for a record 18 months, twice as long as the Great Comet of 1811. At perihelion, it shone brighter than any star in the sky except Sirius, and its two tails stretched 30-40 degrees across the sky. The passage of Hale-Bopp was notable also for inciting a degree of panic about comets not seen for decades. Rumours that the comet was being followed by an alien spacecraft inspired a mass suicide among followers of the Heaven's Gate cult. -
Photo credit: Mars Reconnaissance OrbiterFalse-color Mars Reconnaissance Orbiter image of a side of the Chasma Boreale, a canyon in the polar ice cap of the Planum Boreum (north pole of Mars). Light browns are layers of surface dust, greys and blues are layers of water and carbon dioxide ice. Regular geometric cracking is indicative of higher concentrations of water ice.
The Planum Boreum's permanent ice cap has a maximum depth of 3 km (1.9 mi). It is roughly 1200 km (750 mi) in diameter, an area equivalent to about 1½ times the size of Texas. The Chasma Boreale is up to 100 km (62.5 mi) wide and features scarps up to 2 km (1.25 mi) high. For a comparison, the Grand Canyon is approximately 1.6 km (1 mi) deep in some places and 446 km (279 mi) long but only up to 24 km (15 mi) wide. -
Photo credit: Cassini orbiterThis polar map of Jupiter, taken by the Cassini orbiter as it neared Jupiter during a flyby on its way to Saturn, is the most detailed global color map of the planet ever produced. The south pole is in the center of the map and the equator is at the edge. The map shows a variety of colorful cloud features, including parallel reddish-brown and white bands, the Great Red Spot, multi-lobed chaotic regions, white ovals, and many small vortexes. Many clouds appear in streaks and waves due to continual stretching and folding by Jupiter's winds and turbulence. -
Model: NickshanksLunar distance is a measurement of the distance from the Earth to the Moon. This diagram shows the distance, averaging 384,400 km (238,900 mi), to scale, as well as the Earth and the Moon (scroll to see the entire image). -
Photograph credit: NASA / JPL– Caltech / University of ArizonaAlthough Mars is smaller than the Earth and 50 percent farther from the Sun, its climate has important similarities with the Earth, such as the presence of polar ice caps, seasonal changes and observable weather patterns. This image shows layered deposits in Planum Boreum, in the north polar region of Mars, which formed from a 3-kilometre-thick (2 mi) stack of dusty water-ice layers about 1,000 km (600 mi) across. The layers record information about the climate of the planet stretching back several million years. Erosion has created scarps and troughs that expose the layering. The tan-colored layers are the dusty water ice of the polar layered deposits, however a section of bluish layers is visible below them. These bluish layers contain sand-sized rock fragments that likely formed a large polar dunefield before the overlying dusty ice was deposited. This photograph, depicting an area approximately 1.3 km (0.8 mi) across, was captured by the HiRISE camera on board NASA's Mars Reconnaissance Orbiter.
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Pierre-Simon Laplace, one of the originators of the nebular hypothesis (from Formation and evolution of the Solar System) -
Diagram of the Sun's magnetosphere and helioshealth (from Solar System) -
To-scale diagram of distance between planets, with the white bar showing orbital variations. The size of the planets is not to scale. (from Solar System) -
True-scale Solar System diagram made by Emanuel Bowen in 1747. At that time, Uranus, Neptune, nor the asteroid belts have been discovered yet. (from Solar System) -
Plot of objects around the Kuiper belt and other asteroid populations. J, S, U and N denotes Jupiter, Saturn, Uranus and Neptune. (from Solar System) -
Neptune and its moon Triton, taken by Voyager 2. Triton's orbit will eventually take it within Neptune's Roche limit, tearing it apart and possibly forming a new ring system. (from Formation and evolution of the Solar System) -
Diagram of the early Solar System's protoplanetary disk, out of which Earth and other Solar System bodies formed (from Solar System) -
Meteor Crater in Arizona. Created 50,000 years ago by an impactor about 50 metres (160 ft) across, it shows that the accretion of the Solar System is not over. (from Formation and evolution of the Solar System) -
Animations of the Solar System's outer planets orbiting. This animation is 100 times faster than the inner planet animation. (from Solar System) -
Artist's conception of the giant impact thought to have formed the Moon (from Formation and evolution of the Solar System) -
Hubble image of protoplanetary discs in the Orion Nebula, a light-years-wide stellar nursery probably very similar to the primordial nebula from which the Sun formed (from Formation and evolution of the Solar System) -
The Sun in true white color (from Solar System) -
Comparison between the habitable zones of the Solar System and Gliese 581 (planet d was later found to not exist). The habitable zone is highly dependent on parent star's luminosity. (from Solar System) -
The orbital eccentricities and inclinations of the scattered disc population compared to the classical and resonant Kuiper belt objects (from Solar System) -
The motion of 'lights' moving across the sky is the basis of the classical definition of planets: wandering stars. (from Solar System)
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Relative size of the Sun as it is now (inset) compared to its estimated future size as a red giant (from Formation and evolution of the Solar System) -
The current Sun compared to its peak size in the red-giant phase (from Solar System)
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Comet Hale–Bopp seen in 1997 (from Solar System) -
Simulation showing outer planets and Kuiper belt:
a) Before Jupiter/Saturn 2:1 resonance
b) Scattering of Kuiper belt objects into the Solar System after the orbital shift of Neptune
c) After ejection of Kuiper belt bodies by JupiterOrbit of JupiterOrbit of SaturnOrbit of UranusOrbit of Neptune(from Formation and evolution of the Solar System) -
Artist's conception of a protoplanetary disk (from Formation and evolution of the Solar System) -
Animations of the Solar System's inner planets orbiting. Each frame represents 2 days of motion. (from Solar System) -
Location of the Solar System within the Milky Way (from Formation and evolution of the Solar System) -
Orbit classification of Kuiper belt objects. Some clusters that is subjected to orbital resonance are marked. (from Solar System) -
The Solar System within the interstellar medium, with the different regions and their distances on a steped horizontal distance scale (from Solar System) -
The outer planets Jupiter, Saturn, Uranus and Neptune, compared to the inner planets Earth, Venus, Mars, and Mercury at the bottom right (from Solar System) -
The orbits of Sedna, 2012 VP113, Leleākūhonua, and other very distant objects along with the predicted orbit of the hypothetical Planet Nine (from Solar System) -
The Sun, planets, moons and dwarf planets. The asteroid belt and Kuiper belt are not added because the individual asteroids are too small to be shown on the diagram. -
Overview of the inner Solar System up to Jupiter's orbit (from Solar System) -
The Ring nebula, a planetary nebula similar to what the Sun will become (from Formation and evolution of the Solar System) -
Diagram of the Milky Way, with galactic features and the relative position of the Solar System labelled. (from Solar System) -
Diagram of the Local Interstellar Cloud, the G-Cloud and surrounding stars. As of 2022, the precise location of the Solar System in the clouds is an open question in astronomy. (from Solar System)
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Did you know –
- ... that Jupiter is the only planet capable of pulling an interstellar comet into a Sun-centered orbit?
- ...that the Solar Sentinels, a NASA spacecraft designed to study the Sun, will have to survive at distances from the Sun only one-quarter of Earth's distance?
- ...that just over 50 kilometres above its surface, the atmosphere of Venus has very similar pressure and temperature as does Earth, making it the most Earth-like area in the Solar System?
- ...that NASA conducts field trials, called Desert RATS, for new technologies for manned exploration of the surface of the Moon, Mars, or beyond?
- ...that scarps, ridges, and troughs, such as the 650 km long and 2 km high Discovery Rupes cutting through the Rameau crater, are common features in the Discovery quadrangle on the planet Mercury?
- ...that the Kármán line dividing the Earth's atmosphere and outer space is defined by the Fédération Aéronautique Internationale as 100 km above mean sea level?
- ...that Mars' south polar ice cap may be melting due to global warming?
- ...that Lowell Observatory staff resisted building the telescope used to discover the dwarf planet Pluto until trustee Roger Putnam ordered them to do so?
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Solar System: Planets ( Definition · Planetary habitability · Terrestrial planets · Gas giants · Rings) · Dwarf planets ( Plutoid) · Colonization · Discovery timelineˑ Exploration · Moons · Planetariums
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- Mercury: Geology · Exploration ( Mariner 10 · MESSENGER · BepiColombo) · Transit
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Earth:
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- 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) · Exploration ( New Horizons)
- Haumea: Moons ( Hi'iaka, Namaka)
- Makemake
- Eris: Dysnomia
- 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
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