Planets & Moons
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Sun
Mass 1.9885e30 kg
Mean radius 696,392 km
Volume 1.41e18 km³
Average density 1.408 g/cm³
Equatorial surface gravity 274 m/s² 28 g
Rotation period 25.05 day
Escape velocity (surface) 617.7 km/s
Planets Eight
The Sun is a G-type main-sequence star (G2V) based on its spectral
class. As such, it is informally and not completely accurately
referred to as a yellow dwarf (its light is closer to white than
yellow). It formed approximately 4.6 billion years ago from
the gravitational collapse of matter within a region of a large
molecular cloud. Most of this matter gathered in the center, whereas
the rest flattened into an orbiting disk that became the Solar System.
The central mass became so hot and dense that it eventually initiated
nuclear fusion in its core. It is thought that almost all stars form
by this process.
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Mercury ☿
Mass 3.3022e23 kg
Mean radius 2,439.7 km
Volume 6.083e10 km³
Aphelion 69,816,900 km
Perihelion 46,001,200 km
Orbital period 87.969 days
Equatorial surface gravity 3.7 m/s² 0.38 g
Rotation period 58.646 day
Escape velocity (surface) 4.25 km/s
Satellites None
Mercury is the innermost and smallest planet in the
Solar System. The orbit of Mercury has the highest
eccentricity of all the Solar System planets, and it
has the smallest axial tilt. It completes three
rotations about its axis for every two orbits. The
perihelion of Mercury's orbit precesses around the Sun
at an excess of 43 arcseconds per century; a phenomenon
that was explained in the 20th century by Albert
Einstein's General Theory of Relativity. Mercury is
bright when viewed from Earth, ranging from −2.3 to 5.7
in apparent magnitude, but is not easily seen as its
greatest angular separation from the Sun is only 28.3°.
Since Mercury is normally lost in the glare of the Sun,
unless there is a solar eclipse it can be viewed from
Earth's Northern Hemisphere only in morning or evening
twilight, while its extreme elongations occur in
Declinations south of the celestial equator, such that
it can be seen at favorable apparitions from moderate
latitudes in the Southern Hemisphere in a fully dark
sky.
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Venus ♀
Mass 4.8675e24 kg
Mean radius 6,052 km
Volume 9.2843e11 km³
Aphelion 108,939,000 km
Perihelion 107,477,000 km
Orbital period 224.701 days
Equatorial surface gravity 8.87 m/s² 0.904 g
Rotation period 243.025 day
Escape velocity (surface) 10.36 km/s
Satellites None
Venus is a terrestrial planet and is sometimes called Earth's
"sister planet" because of their similar size, mass, proximity to the
Sun, and bulk composition. It is radically different from Earth in
other respects. It has the densest atmosphere of the four terrestrial
planets, consisting of more than 96% carbon dioxide. The atmospheric
pressure at the planet's surface is 92 times that of Earth, or roughly
the pressure found 900 m underwater on Earth. Venus is by
far the hottest planet in the Solar System, with a mean surface
temperature of 462°C, even though Mercury is closer
to the Sun. Venus is shrouded by an opaque layer of highly reflective
clouds of sulfuric acid, preventing its surface from being seen from
space in visible light. It may have had water oceans in the
past, but these would have vaporized as the temperature rose
due to a runaway greenhouse effect. The water has probably
photodissociated, and the free hydrogen has been swept into
interplanetary space by the solar wind because of the lack of a
planetary magnetic field. Venus's surface is a dry desertscape
interspersed with slab-like rocks and is periodically resurfaced by
volcanism.
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Earth ⊕
Mass 5.97e24 kg
Mean radius 6,371 km, 6.37e6 meters
Earth GM = 3.98e14
Volume 1.083e12 km³
Aphelion 152100000 km
Perihelion 147095000 km
Orbital period 365.256363004 days
Equatorial surface gravity 9.8 m/s² 1.0 g
Rotation period 0.99726968 day
Escape velocity (surface) 11.186 km/s
Satellites: one, moon
Earth is the third planet from the Sun and the only astronomical
object known to harbor life. According to radiometric dating and other
sources of evidence, Earth formed over 4.5 billion years
ago. Earth's gravity interacts with other objects in
space, especially the Sun and the Moon, Earth's only natural
satellite. Earth revolves around the Sun in 365.26 days, a period
known as an Earth year. During this time, Earth rotates about its axis
about 366.26 times.
Earth's axis of rotation is tilted with respect to its orbital plane,
producing seasons on Earth. The gravitational interaction between
Earth and the Moon causes ocean tides, stabilizes Earth's orientation
on its axis, and gradually slows its rotation. Earth is the
densest planet in the Solar System and the largest of the four
terrestrial planets.
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Moon
Mass 7.342e23 kg
Mean radius 1737 km
Volume 2.1958e10 km³
Apogee 405400 km
Perigee 362600 km
Orbital period 27.321661 days. time taken for the moon to
make one complete orbit about the earth, referenced to the stars.
Synodic period 29.530 days. time that it takes
for the moon to reappear at the same point in relation
to a fixed point on the earth.
Equatorial surface gravity 1.62 m/s² 0.165 g
the Orbital period is 27.321 days
Rotation period 27.321661 day
Escape velocity (surface) 2.38 km/s
Satellites None
The Moon is an astronomical body that orbits planet Earth and is
Earth's only permanent natural satellite. It is the fifth-largest
natural satellite in the Solar System, and the largest among planetary
satellites relative to the size of the planet that it orbits (its
primary). The Moon is after Jupiter's satellite Io the second-densest
satellite in the Solar System among those whose densities are known.
The Moon is thought to have formed about 4.51 billion years ago, not
long after Earth. The most widely accepted explanation is that the
Moon formed from the debris left over after a giant impact between
Earth and a Mars-sized body called Theia.
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Mars ♂
Mass 6.4171e23 kg
Mean radius 3389 km
Volume 1.6318e11 km³
Aphelion 249200000 km
Perihelion 206700000 km
Orbital period 686.971 days
Equatorial surface gravity 3.72076 m/s² 0.3794 g
Rotation period 1.025957 day
Escape velocity (surface) 5.027 km/s
Satellites: Phobos & Deimos
Mars is the fourth planet from the Sun and the second-smallest planet
in the Solar System after Mercury. In English, Mars carries a name of
the Roman god of war, and is often referred to as the "Red
Planet" because the reddish iron oxide prevalent on its surface
gives it a reddish appearance that is distinctive among the astronomical
bodies visible to the naked eye. Mars is a terrestrial planet with a
thin atmosphere, having surface features reminiscent both of the impact
craters of the Moon and the valleys, deserts, and polar ice caps of
Earth.
The rotational period and seasonal cycles of Mars are likewise similar
to those of Earth, as is the tilt that produces the seasons. Mars is the
site of Olympus Mons, the largest volcano and second-highest known
mountain in the Solar System, and of Valles Marineris, one of the
largest canyons in the Solar System. The smooth Borealis basin in the
northern hemisphere covers 40% of the planet and may be a giant impact
feature. Mars has two moons, Phobos and Deimos, which are small
and irregularly shaped. These may be captured asteroids, similar to 5261
Eureka, a Mars trojan.
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Phobos
Mass 1.0659e16 kg
Mean radius 11.2667 km
Volume 5783.61 km³
Apoapsis 9517.58 km
Periapsis 9234.42 km
Orbital period 0.31891 days
Equatorial surface gravity 0.0057 m/s² 581.4 µg
Rotation period Synchronous
Escape velocity (surface) 11.39 m/s
Phobos (systematic designation: Mars I) is the innermost and larger
of the two natural satellites of Mars, the other being Deimos. Both
moons were discovered in 1877 by American astronomer Asaph Hall.
Phobos is a small, irregularly shaped object with a mean radius of 11 km
and is seven times as massive as the outer moon, Deimos. Phobos is named
after the Greek god Phobos, a son of Ares (Mars) and Aphrodite (Venus)
and the personification of fear (cf. phobia).
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Deimos
Mass 1.4762e15 kg
Mean radius 6.2 km
Volume 999.78 km³
Apoapsis 23470 km
Periapsis 23455 km
Orbital period 1.263 days
Equatorial surface gravity 0.003 m/s² 306 µg
Rotation period Synchronous
Escape velocity (surface) 5.556 m/s
Deimos (systematic designation: Mars II) is the smaller and
outermost of the two natural satellites of the planet Mars, the other
being Phobos. Deimos has a mean radius of 6.2 km and takes 30.3
hours to orbit Mars. Deimos is 23,460 km from Mars, much
further than Mars's other moon, Phobos. It is named for Deimos who in
Greek mythology is the twin brother of Phobos, and personifies terror.
Deimos was discovered by Asaph Hall, III at the United States Naval
Observatory in Washington, D.C. on 12 August 1877, at about 07:48 UTC.
Hall also discovered Phobos on 18 August 1877, at about 09:14 GMT, after
deliberately searching for Martian moons.
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Jupiter ♃
Mass 1.8986e27 kg
Equatorial radius 71,492 km
Polar radius 66,854 km
Volume 1.43128e15 km³
Aphelion 816,520,800 km
Perihelion 740,573,600 km
Orbital period 4,332 days
Equatorial surface gravity 24.79 m/s² 2.528 g
Rotation period 9.925 hours
Escape velocity (surface) 59.5 km/s
Satellites 79
Jupiter is the fifth planet from the Sun and the
largest planet within the Solar System. It is a gas
giant with a mass slightly less than one-thousandth of
the Sun but is two and a half times the mass of all the
other planets in our Solar System combined. Jupiter is
classified as a gas giant along with Saturn, Uranus and
Neptune. Together, these four planets are sometimes
referred to as the Jovian or outer planets.
It is primarily composed of hydrogen with a quarter of its mass
being helium, though helium comprises only about a tenth of the number
of molecules. It may also have a rocky core of heavier elements, but
like the other giant planets, Jupiter lacks a well-defined solid
surface. Because of its rapid rotation, the planet's shape is that of an
oblate spheroid (it has a slight but noticeable bulge around the
equator). The outer atmosphere is visibly segregated into several bands
at different latitudes, resulting in turbulence and storms along their
interacting boundaries. A prominent result is the Great Red Spot, a
giant storm that is known to have existed since at least the 17th
century when it was first seen by telescope.
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Ganymede
Mass 1.4819e23 kg
Mean radius 2634 km
Volume 1.4819e23 km³
Apoapsis 1071600 km
Periapsis 1069200 km
Orbital period 7.154 days
Equatorial surface gravity 1.428 m/s² 0.146 g
Rotation period synchronous
Escape velocity (surface) 2.741 km/s
Ganymede (Jupiter III) is the largest and most
massive moon of Jupiter and in the Solar System. The ninth largest
object in the Solar System, it is the largest without a substantial
atmosphere. It has a diameter of 5,268 km and is 8% larger
than the planet Mercury, although only 45% as massive. Possessing a
metallic core, it has the lowest moment of inertia factor of any solid
body in the Solar System and is the only moon known to have a magnetic
field. Outward from Jupiter, it is the seventh satellite and the third
of the Galilean moons, the first group of objects discovered orbiting
another planet. Ganymede orbits Jupiter in roughly seven days and is
in a 1:2:4 orbital resonance with the moons Europa and Io, respectively.
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Europa
Mass 4.800e22 kg
Mean radius 1561 km
Volume 1.593e10 km³
Apoapsis 676938 km
Periapsis 664862 km
Orbital period 3.551 days
Equatorial surface gravity 1.314 m/s² 0.134 g
Rotation period synchronous
Escape velocity (surface) 2.025 km/s
Europa (Jupiter
II) is the smallest of the four Galilean moons orbiting Jupiter, and the
sixth-closest to the planet of all the 79 known moons of Jupiter. It is
also the sixth-largest moon in the Solar System. Europa was discovered
in 1610 by Galileo Galilei and was named after Europa, the Phoenician
mother of King Minos of Crete and lover of Zeus.
Slightly smaller than Earth's Moon, Europa is primarily made of
silicate rock and has a water-ice crust and probably an iron–nickel
core. It has a very thin atmosphere composed primarily of oxygen. Its
surface is striated by cracks and streaks, but craters are relatively
few. In addition to Earth-bound telescope observations, Europa has been
examined by a succession of space probe flybys, the first occurring in
the early 1970s.
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Io
Mass 8.9319e22 kg
Mean radius 1821.6 km
Volume 2.53e10 km³
Apoapsis 423400 km
Periapsis 420000 km
Orbital period 1.7691 days
Equatorial surface gravity 1.796 m/s² 0.183 g
Rotation period synchronous
Escape velocity (surface) 2.558 km/s
Io (Jupiter I) is the innermost of the four Galilean moons of the
planet Jupiter. It is the fourth-largest moon, has the highest density
of all the moons, and has the least amount of water of any known
astronomical object in the Solar System. It was discovered in 1610 and
was named after the mythological character Io, a priestess of Hera who
became one of Zeus' lovers.
With over 400 active volcanoes, Io is the most geologically active
object in the Solar System. This extreme geologic activity is the
result of tidal heating from friction generated within Io's interior as
it is pulled between Jupiter and the other Galilean satellites—Europa,
Ganymede and Callisto. Several volcanoes produce plumes of sulfur and
sulfur dioxide that climb as high as 500 km above the surface.
Io's surface is also dotted with more than 100 mountains that have been
uplifted by extensive compression at the base of Io's silicate crust.
Some of these peaks are taller than Mount Everest. Unlike most
satellites in the outer Solar System, which are mostly composed of water
ice, Io is primarily composed of silicate rock surrounding a molten iron
or iron-sulfide core. Most of Io's surface is composed of extensive
plains coated with sulfur and sulfur-dioxide frost.
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Callisto
Mass 1.0759e23 kg
Mean radius 2410 km
Volume 5.9e10 km³
Apoapsis 1897000 km
Periapsis 1869000 km
Orbital period 16.6890 days
Equatorial surface gravity 1.235 m/s² 0.126 g
Rotation period synchronous
Escape velocity (surface) 2.440 km/s
Callisto (Jupiter IV) is the second-largest moon of
Jupiter, after Ganymede. It is the third-largest moon in the Solar
System after Ganymede and Saturn's largest moon Titan, and the largest
object in the Solar System not to be properly differentiated. Callisto
was discovered in 1610 by Galileo Galilei. At 4821 km in diameter,
Callisto has about 99% the diameter of the planet Mercury but only about
a third of its mass. It is the fourth Galilean moon of Jupiter by
distance, with an orbital radius of about 1883000 km. It is not in an
orbital resonance like the three other Galilean satellites—Io, Europa,
and Ganymede—and is thus not appreciably tidally heated. Callisto's
rotation is tidally locked to its orbit around Jupiter, so that the same
hemisphere always faces inward; Jupiter appears to stand nearly still in
Callisto's sky. It is less affected by Jupiter's magnetosphere than the
other inner satellites because of its more remote orbit, located just
outside Jupiter's main radiation belt.
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Saturn ♄
Mass 5.6834e26 kg
Mean radius 58,232 km
Volume 8.2713e14 km³
Aphelion 1,514.50e6 km
Perihelion 1,352.55e6 km
Orbital period 10,759.22 days
Equatorial surface gravity 10.44 m/s² 1.065 g
Rotation period 10h 33m
Escape velocity (surface) 35.5 km/s
Satellites 62 plus rings
Saturn is the sixth planet from the Sun and the second-largest in the
Solar System, after Jupiter. It is a gas giant with an average radius
about nine times that of Earth. It has only one-eighth the
average density of Earth, but with its larger volume Saturn is over 95
times more massive. Saturn is named after the Roman god of
agriculture; its astronomical symbol (♄) represents the god's sickle.
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Titan
Mass 1.345e23 kg
Mean radius 2574 km
Volume 7.16e10 km³
Apoapsis 1257060 km
Periapsis 1186680 km
Orbital period 15.945 days
Equatorial surface gravity 1.352 m/s² 0.14 g
Rotation period Synchronous
Escape velocity (surface) 2.639 km/s
Titan is the largest moon of Saturn. It is the only moon known to
have a dense atmosphere, and the only object in space, other than Earth,
where clear evidence of stable bodies of surface liquid have been found.
Titan is the sixth gravitationally rounded moon from Saturn.
Frequently described as a planet-like moon, Titan is 50% larger than
Earth's moon and 80% more massive. It is the second-largest moon in the
Solar System after Jupiter's moon Ganymede, and is larger than the
smallest planet, Mercury, but only 40% as massive.
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Uranus ♅
Mass 8.6810e25 kg
Mean radius 25,362 km
Volume 6.833e13 km³
Aphelion 3008 Gm
Perihelion 2742 Gm
Orbital period 30,688.5 days
Equatorial surface gravity 8.69 m/s² 0.886 g
Rotation period 0.71833 d day
Escape velocity (surface) 21.3 km/s
Satellites 27
Uranus (from the Latin name "Ūranus" for the Greek god Οὐρανός) is
the seventh planet from the Sun. It has the third-largest planetary
radius and fourth-largest planetary mass in the Solar System. Uranus is
similar in composition to Neptune, and both have bulk chemical
compositions which differ from that of the larger gas giants Jupiter and
Saturn. For this reason, scientists often classify Uranus and Neptune as
"ice giants" to distinguish them from the gas giants. Uranus' atmosphere
is similar to Jupiter's and Saturn's in its primary composition of
hydrogen and helium, but it contains more "ices" such as water, ammonia,
and methane, along with traces of other hydrocarbons. It is the
coldest planetary atmosphere in the Solar System, with a minimum
temperature of 49 K, and has a complex, layered cloud
structure with water thought to make up the lowest clouds and methane
the uppermost layer of clouds. The interior of Uranus is mainly composed
of ices and rock.
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Neptune ♆
Mass 1.02413e26 kg
Mean radius 24,622 km
Volume 6.254e13 km³
Aphelion 4.54 billion km
Perihelion 4.46 billion km
Orbital period 60,182 days
Equatorial surface gravity 11.15 m/s² 1.14 g
Rotation period 0.6713 day
Escape velocity (surface) 23.5 km/s
Satellites 14
Neptune is the eighth and farthest known planet from the Sun in the
Solar System. In the Solar System, it is the fourth-largest planet by
diameter, the third-most-massive planet, and the densest giant planet.
Neptune is 17 times the mass of Earth and is slightly more massive than
its near-twin Uranus, which is 15 times the mass of Earth and slightly
larger than Neptune. Neptune orbits the Sun once every 164.8 years at
an average distance of 4.5 billion km. It is named after the
Roman god of the sea and has the astronomical symbol ♆, a stylised
version of the god Neptune's trident.
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Pluto
Mass 1.303e22 kg
Mean radius 1,188.3 km
Volume 7.057e9 km³
Aphelion 7.37593 billion km
Perihelion 4.43682 billion km
Orbital period 90,560 days
Equatorial surface gravity 0.620 m/s² 0.063 g
Rotation period 6.387230 day
Escape velocity (surface) 1.212 km/s
Satellites 5
Pluto (minor planet designation: 134340 Pluto) is a dwarf planet in
the Kuiper belt, a ring of bodies beyond Neptune. It was the first
Kuiper belt object to be discovered and is the largest known plutoid (or
ice dwarf).
Pluto was discovered by Clyde Tombaugh in 1930 and was originally
considered to be the ninth planet from the Sun. After 1992, its status
as a planet was questioned following the discovery of several objects of
similar size in the Kuiper belt. In 2005, Eris, a dwarf planet in the
scattered disc which is 27% more massive than Pluto, was discovered.
This led the International Astronomical Union (IAU) to define the term
"planet" formally in 2006, during their 26th General Assembly. That
definition excluded Pluto and reclassified it as a dwarf planet.
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Eris
Mass 1.66e22 kg
Mean radius 1163 km
Volume 6.59e9 km³
Aphelion 14.602 billion km
Perihelion 5.723 billion km
Orbital period 203,830 days
Equatorial surface gravity 0.82 m/s² 0.083 g
Rotation period 25.9 day
Escape velocity (surface) 1.38 km/s
Satellites 1
Eris (minor-planet designation 136199 Eris) is the most massive and
second-largest (by volume) dwarf planet (and plutoid) in the known Solar
System. Eris was discovered in January 2005 by a Palomar
Observatory-based team led by Mike Brown, and its discovery was verified
later that year. In September 2006 it was named after Eris, the Greek
goddess of strife and discord. Eris is the ninth most massive object
directly orbiting the Sun, and the 16th most massive overall, because
seven moons are more massive than all known dwarf planets. It is also
the largest which has not yet been visited by a spacecraft. Eris was
measured to be 2,326 kilometers in diameter.
Eris's mass is about 0.27% of the Earth mass, about 27% more than dwarf
planet Pluto, although Pluto is slightly larger by volume.
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Planetary Attributes
Name Equatorial Mass Semi- Orbital Inclination Orbital Rotation Con- Axial Rings Atmosphere
diameter major period to Sun's eccen- period firmed tilt
(note 1) (note 1) axis(AU) (years) equator (°) tricity (days) moons (°)
Sun 109.3 333000 25.05
1. Mercury 0.382 0.06 0.39 0.24 3.38 0.206 58.64 0 0.04 no minimal
2. Venus 0.949 0.82 0.72 0.62 3.86 0.007 −243.02 0 177.36 no CO₂, N₂
3. Earth 1.00 1.00 1.00 1.00 7.25 0.017 1.00 1 23.44 no N₂, O₂, Ar
4. Mars 0.532 0.11 1.52 1.88 5.65 0.093 1.03 2 25.19 no CO₂, N₂, Ar
5. Jupiter 11.209 317.8 5.20 11.86 6.09 0.048 0.41 79 3.13 yes H₂, He
6. Saturn 9.449 95.2 9.54 29.46 5.51 0.054 0.43 62 26.73 yes H₂, He
7. Uranus 4.007 14.6 19.22 84.01 6.48 0.047 −0.72 27 97.77 yes H₂, He, CH₄
8. Neptune 3.883 17.2 30.06 164.8 6.43 0.009 0.67 14 28.32 yes H₂, He, CH₄
Pluto 0.187 0.0022 39.48 248.0 11.88 0.249 6.39 5 122.53 no N₂, CH₄, CO
Eris 0.182 0.0027 67.78 558.0 44.04 0.441 1.08 1 44 no CH₄
Note 1: Earth = 1
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