Evolutionary:Example system: Difference between revisions
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Example pages: Humans and the Sol system, at the level of detail of real articles |
Example system: fuller planet sections |
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| temperature = −173 ~ 427 °C | | temperature = −173 ~ 427 °C | ||
}} | }} | ||
'''Mercury''' is the smallest planet and the closest to the Sun. With almost no atmosphere to hold heat, its surface swings | '''Mercury''' is the smallest planet and the closest to the Sun, orbiting at an average distance of 58 million km. It is only slightly larger than Earth's moon, which its heavily cratered surface closely resembles. Its largest impact feature, the Caloris Basin, is around 1,550 km across. Long cliffs called lobate scarps run across the surface, formed as the planet's interior cooled and shrank. | ||
Mercury rotates three times for every two orbits, so a single day, from one sunrise to the next, lasts 176 Earth days. With almost no atmosphere to hold heat, its surface swings from around 427 °C in daylight to −173 °C at night. Despite this, water ice survives in permanently shadowed craters near its poles. Its iron core is unusually large, taking up around 85 percent of the planet's radius. | |||
=== Venus === | === Venus === | ||
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| gravity = 0.90 g | | gravity = 0.90 g | ||
| atmosphere = Carbon dioxide (96.5%), nitrogen; ~92 times Earth's pressure | | atmosphere = Carbon dioxide (96.5%), nitrogen; ~92 times Earth's pressure | ||
| temperature = | | temperature = About 464 °C | ||
}} | }} | ||
'''Venus''' is almost the same size as Earth, but | '''Venus''' is almost the same size and mass as Earth, and is sometimes called its sister planet, but the two could hardly be more different. Its dense carbon dioxide atmosphere presses down with about 92 times Earth's surface pressure, comparable to being 900 m under the sea. The resulting runaway greenhouse effect makes it the hottest planet in the system, hotter even than Mercury, at around 464 °C: hot enough to melt lead. | ||
Thick clouds of sulphuric acid hide its surface completely, and reflect so much sunlight that Venus is the brightest natural object in the night sky after Earth's moon. It rotates backwards, and so slowly that one rotation takes longer than its year. Its volcanic plains have relatively few craters, suggesting the whole surface was renewed a few hundred million years ago. The longest any lander has survived there is just over two hours. | |||
=== Earth === | === Earth === | ||
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| gravity = 1 g | | gravity = 1 g | ||
| atmosphere = Nitrogen (78%), oxygen (21%) | | atmosphere = Nitrogen (78%), oxygen (21%) | ||
| temperature = | | temperature = About 15 °C (average) | ||
| surface = ~71% water | | surface = ~71% water | ||
| native_species = [[Evolutionary:Example species|Humans]] and millions of other species | | native_species = [[Evolutionary:Example species|Humans]] and millions of other species | ||
}} | }} | ||
'''Earth''' | '''Earth''' orbits the Sun at an average distance of about 150 million km, within the range where water can stay liquid on a planet's surface. Oceans cover around 71 percent of it, and it is the only world in the system known to support life. Its oxygen-rich atmosphere is itself a product of life: almost all of its oxygen was released by photosynthesising organisms over billions of years. | ||
A liquid iron outer core generates a magnetic field that shields the surface from the solar wind, while plate tectonics slowly recycles its crust. Its moon, about a quarter of Earth's diameter, is unusually large for its planet and probably formed from debris thrown out by a giant collision early in Earth's history. The Moon drives Earth's ocean tides and stabilises the tilt of its axis, keeping its seasons and climate relatively steady over long periods. Earth is the homeworld of [[Evolutionary:Example species|humans]]. | |||
=== Mars === | === Mars === | ||
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| gravity = 0.38 g | | gravity = 0.38 g | ||
| atmosphere = Carbon dioxide (95%); under 1% of Earth's pressure | | atmosphere = Carbon dioxide (95%); under 1% of Earth's pressure | ||
| temperature = | | temperature = About −60 °C (average) | ||
}} | }} | ||
'''Mars''' is a cold desert world whose red colour comes from iron oxide dust. Dry riverbeds and lake deposits show that liquid water once flowed | '''Mars''' is a cold desert world about half the diameter of Earth, whose red colour comes from iron oxide dust covering its surface. Its atmosphere is less than 1 percent as dense as Earth's, too thin to keep liquid water stable on the surface. Temperatures average about −60 °C, and its poles are capped with water ice and frozen carbon dioxide. Planet-wide dust storms can hide the entire surface for weeks. | ||
It holds some of the largest landforms in the system: Olympus Mons, a shield volcano around 22 km high, and Valles Marineris, a canyon system roughly 4,000 km long. Dry riverbeds, deltas, and lake deposits show that liquid water once flowed across its surface billions of years ago. Its two small moons, Phobos and Deimos, may be captured asteroids. After Earth, Mars is the most explored planet in the system, visited by many orbiters and several rovers. | |||
=== Jupiter === | === Jupiter === | ||
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| gravity = 2.53 g (at the cloud tops) | | gravity = 2.53 g (at the cloud tops) | ||
| atmosphere = Hydrogen, helium | | atmosphere = Hydrogen, helium | ||
| temperature = | | temperature = About −110 °C (cloud tops) | ||
}} | }} | ||
'''Jupiter''' is the largest planet, more than twice as massive as all the other planets combined. Its Great Red Spot | '''Jupiter''' is the largest planet, about 318 times the mass of Earth and more than twice as massive as all the other planets combined. It has no solid surface: its atmosphere of hydrogen and helium simply grows denser with depth. Its rapid rotation, under 10 hours, flattens it visibly at the poles and stretches its clouds into the planet's distinctive bands. The Great Red Spot, a storm wider than Earth, has been observed continuously since at least the 19th century. | ||
Jupiter has the strongest magnetic field of any planet, surrounded by radiation belts intense enough to damage spacecraft. Its four largest moons, the Galilean moons, are worlds in their own right. Io is the most volcanically active body in the system; Europa likely hides a liquid water ocean beneath its icy crust; Ganymede is the largest moon in the system, bigger than Mercury; and Callisto is one of the most heavily cratered objects known. | |||
=== Saturn === | === Saturn === | ||
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| gravity = 1.07 g (at the cloud tops) | | gravity = 1.07 g (at the cloud tops) | ||
| atmosphere = Hydrogen, helium | | atmosphere = Hydrogen, helium | ||
| temperature = | | temperature = About −140 °C (cloud tops) | ||
}} | }} | ||
'''Saturn''' is best known for its | '''Saturn''' is the second-largest planet, around 95 times the mass of Earth, and the least dense: on average it is less dense than water. It is best known for its ring system, which spans more than 270,000 km but is, in most places, only tens of metres thick. The rings are made of countless pieces of water ice, from grains of dust to boulders the size of houses. A persistent six-sided cloud pattern circles its north pole. | ||
Saturn's largest moon, Titan, is bigger than Mercury and is the only moon in the system with a thick atmosphere. Its surface has rivers, lakes, and seas of liquid methane and ethane, fed by methane rain. Another moon, Enceladus, sprays jets of water vapour and ice from a hidden ocean out through cracks near its south pole. | |||
=== Uranus === | === Uranus === | ||
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| gravity = 0.90 g (at the cloud tops) | | gravity = 0.90 g (at the cloud tops) | ||
| atmosphere = Hydrogen, helium, methane | | atmosphere = Hydrogen, helium, methane | ||
| temperature = | | temperature = About −195 °C (cloud tops) | ||
}} | }} | ||
'''Uranus''' is tilted almost completely on its side, with an axial tilt of about 98 degrees, | '''Uranus''' is an ice giant: beneath its hydrogen and helium atmosphere, most of its mass is a hot, dense fluid of water, ammonia, and methane surrounding a small rocky core. Methane in the upper atmosphere absorbs red light, giving the planet its pale cyan colour. Its atmosphere is the coldest of any planet, reaching around −224 °C. | ||
Uranus is tilted almost completely on its side, with an axial tilt of about 98 degrees, probably the result of a giant collision long ago. As a result, each pole spends around 42 years in continuous sunlight followed by 42 years of darkness. It has a faint system of 13 known rings. Uranus was the first planet discovered with a telescope, in 1781, and has been visited by only one spacecraft, ''Voyager 2'', in 1986. | |||
=== Neptune === | === Neptune === | ||
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| gravity = 1.14 g (at the cloud tops) | | gravity = 1.14 g (at the cloud tops) | ||
| atmosphere = Hydrogen, helium, methane | | atmosphere = Hydrogen, helium, methane | ||
| temperature = | | temperature = About −200 °C (cloud tops) | ||
}} | }} | ||
'''Neptune''' is the outermost planet | '''Neptune''' is the outermost planet, orbiting about 4.5 billion km from the Sun; a single orbit takes nearly 165 years. It was the first planet found by mathematical prediction rather than by searching the sky: irregularities in Uranus's orbit led astronomers to calculate where an unseen planet must be, and it was spotted there in 1846. | ||
Despite receiving very little sunlight, Neptune has the fastest winds in the system, reaching over 2,000 km/h. Its largest moon, Triton, orbits backwards, against the planet's rotation, and is probably a captured Kuiper belt object. Triton is one of the few geologically active moons, with geysers of nitrogen gas. Like Uranus, Neptune has been visited only by ''Voyager 2'', which flew past in 1989. | |||
== Life == | == Life == | ||
Latest revision as of 08:51, 23 October 2026
The Sol system, also called the Solar System, is a single-star system consisting of the Sun and everything bound to it by gravity: eight planets, at least five dwarf planets, hundreds of moons, and countless smaller bodies. It lies in the Orion Arm of the Milky Way, roughly 26,000 light-years from the galactic centre.
Sol is the home system of humans, and its third planet, Earth, is the only world in it known to host life. Its planets divide neatly into two groups: four small, rocky inner worlds, and four giant outer worlds made mostly of gas and ice.
Overview
The Sun contains about 99.86 percent of the system's total mass. It is a G-type main-sequence star, about 4.6 billion years old and roughly halfway through its life on the main sequence. Its light reaches Earth in about 8 minutes and 20 seconds.
The system formed around 4.6 billion years ago from the collapse of part of a cold molecular cloud. Most of the material gathered at the centre to form the Sun, while the remainder flattened into a spinning disc in which the planets assembled. This is why all eight planets orbit in nearly the same plane, and in the same direction.
Beyond the planets lie three reservoirs of smaller bodies:
- The asteroid belt, between Mars and Jupiter, home to rocky and metallic asteroids and the dwarf planet Ceres.
- The Kuiper belt, a wide ring of icy bodies beyond Neptune, including the dwarf planet Pluto.
- The Oort cloud, a vast, thinly scattered shell of icy objects thought to extend more than a light-year from the Sun, and the source of long-period comets.
Planets
Mercury
Mercury is the smallest planet and the closest to the Sun, orbiting at an average distance of 58 million km. It is only slightly larger than Earth's moon, which its heavily cratered surface closely resembles. Its largest impact feature, the Caloris Basin, is around 1,550 km across. Long cliffs called lobate scarps run across the surface, formed as the planet's interior cooled and shrank.
Mercury rotates three times for every two orbits, so a single day, from one sunrise to the next, lasts 176 Earth days. With almost no atmosphere to hold heat, its surface swings from around 427 °C in daylight to −173 °C at night. Despite this, water ice survives in permanently shadowed craters near its poles. Its iron core is unusually large, taking up around 85 percent of the planet's radius.
Venus
Venus is almost the same size and mass as Earth, and is sometimes called its sister planet, but the two could hardly be more different. Its dense carbon dioxide atmosphere presses down with about 92 times Earth's surface pressure, comparable to being 900 m under the sea. The resulting runaway greenhouse effect makes it the hottest planet in the system, hotter even than Mercury, at around 464 °C: hot enough to melt lead.
Thick clouds of sulphuric acid hide its surface completely, and reflect so much sunlight that Venus is the brightest natural object in the night sky after Earth's moon. It rotates backwards, and so slowly that one rotation takes longer than its year. Its volcanic plains have relatively few craters, suggesting the whole surface was renewed a few hundred million years ago. The longest any lander has survived there is just over two hours.
Earth
Earth orbits the Sun at an average distance of about 150 million km, within the range where water can stay liquid on a planet's surface. Oceans cover around 71 percent of it, and it is the only world in the system known to support life. Its oxygen-rich atmosphere is itself a product of life: almost all of its oxygen was released by photosynthesising organisms over billions of years.
A liquid iron outer core generates a magnetic field that shields the surface from the solar wind, while plate tectonics slowly recycles its crust. Its moon, about a quarter of Earth's diameter, is unusually large for its planet and probably formed from debris thrown out by a giant collision early in Earth's history. The Moon drives Earth's ocean tides and stabilises the tilt of its axis, keeping its seasons and climate relatively steady over long periods. Earth is the homeworld of humans.
Mars
Mars is a cold desert world about half the diameter of Earth, whose red colour comes from iron oxide dust covering its surface. Its atmosphere is less than 1 percent as dense as Earth's, too thin to keep liquid water stable on the surface. Temperatures average about −60 °C, and its poles are capped with water ice and frozen carbon dioxide. Planet-wide dust storms can hide the entire surface for weeks.
It holds some of the largest landforms in the system: Olympus Mons, a shield volcano around 22 km high, and Valles Marineris, a canyon system roughly 4,000 km long. Dry riverbeds, deltas, and lake deposits show that liquid water once flowed across its surface billions of years ago. Its two small moons, Phobos and Deimos, may be captured asteroids. After Earth, Mars is the most explored planet in the system, visited by many orbiters and several rovers.
Jupiter
Jupiter is the largest planet, about 318 times the mass of Earth and more than twice as massive as all the other planets combined. It has no solid surface: its atmosphere of hydrogen and helium simply grows denser with depth. Its rapid rotation, under 10 hours, flattens it visibly at the poles and stretches its clouds into the planet's distinctive bands. The Great Red Spot, a storm wider than Earth, has been observed continuously since at least the 19th century.
Jupiter has the strongest magnetic field of any planet, surrounded by radiation belts intense enough to damage spacecraft. Its four largest moons, the Galilean moons, are worlds in their own right. Io is the most volcanically active body in the system; Europa likely hides a liquid water ocean beneath its icy crust; Ganymede is the largest moon in the system, bigger than Mercury; and Callisto is one of the most heavily cratered objects known.
Saturn
Saturn is the second-largest planet, around 95 times the mass of Earth, and the least dense: on average it is less dense than water. It is best known for its ring system, which spans more than 270,000 km but is, in most places, only tens of metres thick. The rings are made of countless pieces of water ice, from grains of dust to boulders the size of houses. A persistent six-sided cloud pattern circles its north pole.
Saturn's largest moon, Titan, is bigger than Mercury and is the only moon in the system with a thick atmosphere. Its surface has rivers, lakes, and seas of liquid methane and ethane, fed by methane rain. Another moon, Enceladus, sprays jets of water vapour and ice from a hidden ocean out through cracks near its south pole.
Uranus
Uranus is an ice giant: beneath its hydrogen and helium atmosphere, most of its mass is a hot, dense fluid of water, ammonia, and methane surrounding a small rocky core. Methane in the upper atmosphere absorbs red light, giving the planet its pale cyan colour. Its atmosphere is the coldest of any planet, reaching around −224 °C.
Uranus is tilted almost completely on its side, with an axial tilt of about 98 degrees, probably the result of a giant collision long ago. As a result, each pole spends around 42 years in continuous sunlight followed by 42 years of darkness. It has a faint system of 13 known rings. Uranus was the first planet discovered with a telescope, in 1781, and has been visited by only one spacecraft, Voyager 2, in 1986.
Neptune
Neptune is the outermost planet, orbiting about 4.5 billion km from the Sun; a single orbit takes nearly 165 years. It was the first planet found by mathematical prediction rather than by searching the sky: irregularities in Uranus's orbit led astronomers to calculate where an unseen planet must be, and it was spotted there in 1846.
Despite receiving very little sunlight, Neptune has the fastest winds in the system, reaching over 2,000 km/h. Its largest moon, Triton, orbits backwards, against the planet's rotation, and is probably a captured Kuiper belt object. Triton is one of the few geologically active moons, with geysers of nitrogen gas. Like Uranus, Neptune has been visited only by Voyager 2, which flew past in 1989.
Life
Earth is the only place in the system where life is known to exist, including its sole sapient species, humans. Several other worlds are considered possible homes for simple life, past or present:
- Mars, which had liquid water on its surface billions of years ago.
- Europa (Jupiter) and Enceladus (Saturn), which have liquid water oceans beneath their icy crusts.
- Titan (Saturn), with its thick atmosphere and complex organic chemistry.
History
Life appeared on Earth at least 3.5 billion years ago, less than a billion years after the planet formed. Humans began exploring the system directly in the 20th century: the first artificial satellite reached orbit in 1957, the first humans landed on Earth's moon in 1969, and robotic probes have since visited every planet. Voyager 1, launched in 1977, became the first spacecraft to reach interstellar space in 2012.
Behind the scenes
- Written as the example star system page for this wiki, using real-world facts about the Solar System.