"that keeps the far side of the Moon away from the Earth. Mercury is in a 3:2 spin–orbit resonance. The planets' orbits are chaotic over longer timescales, such that the whole Solar System possesses a Lyapunov time in the range of 2–230 million years. In all cases this means that the position of a planet along its orbit ultimately becomes impossible to predict with any certainty (so, for example, the timing of winter and summer become uncertain), but in some cases the orbits themselves may change dramatically. Such chaos manifests most strongly as changes in eccentricity, with some planets' orbits"
"the poles and is lower than the surface gravity of Earth. However, the equatorial escape velocity of nearly is much higher than that for Earth. Saturn is the only planet of the Solar System that is less dense than water—about 30% less. Although Saturn's core is considerably denser than water, the average specific density of the planet is due to the atmosphere. Jupiter has 318 times Earth's mass, and Saturn is 95 times Earth's mass. Together, Jupiter and Saturn hold 92% of the total planetary mass in the Solar System. Despite consisting mostly of hydrogen and helium, most of Saturn's"
"25, 2011 discovery, the densest planet ever discovered, at nearly 20 times the density of Jupiter (about 23 times the density of water). It is slightly more massive than Jupiter. It is thought to be composed of oxygen and carbon (as opposed to hydrogen and helium, the main components of gas giants like Jupiter and Saturn). The oxygen is most likely on the surface of the planet, with increasingly higher quantities of carbon deeper inside the planet. The intense pressure acting upon the planet suggests that the carbon is crystallized, much like diamond is. PSR J1719-1438 b orbits its host"
"from the original solar nebula. The Solar System has four terrestrial planets: Mercury, Venus, Earth, and Mars. Only one terrestrial planet, Earth, is known to have an active hydrosphere. During the formation of the Solar System, there were probably many more terrestrial planetesimals, but most merged with or were ejected by the four terrestrial planets. Dwarf planets, such as Ceres, Pluto and Eris, and small Solar System bodies are similar to terrestrial planets in the fact that they do have a solid surface, but are, on average, composed of more icy materials (Ceres, Pluto and Eris have densities of 2.17,"
"density is the second highest in the Solar System at 5.427 g/cm, only slightly less than Earth's density of 5.515 g/cm. If the effect of gravitational compression were to be factored out from both planets, the materials of which Mercury is made would be denser than those of Earth, with an uncompressed density of 5.3 g/cm versus Earth's 4.4 g/cm. Mercury's density can be used to infer details of its inner structure. Although Earth's high density results appreciably from gravitational compression, particularly at the core, Mercury is much smaller and its inner regions are not as compressed. Therefore, for it"
"uniform density, formula_1. For a differentiated planet or satellite, where there is an increase of density with depth, formula_2. The quantity is a useful indicator of the presence and extent of a planetary core, because a greater departure from the uniform-density value of 0.4 conveys a greater degree of concentration of dense materials towards the center. The Sun has by far the lowest moment of inertia factor value among Solar System bodies; it has by far the highest central density (, compared to ~13 for Earth) and a relatively low average density (1.41 g/cm versus 5.5 for Earth). Saturn has"
"source for chemical abundance, despite their rareness (only five have been recovered on Earth). The planets of the Solar System are divided into two groups: the four inner planets are the terrestrial planets (Mercury, Venus, Earth and Mars), with relatively small sizes and rocky surfaces. The four outer planets are the giant planets, which are dominated by hydrogen and helium and have lower mean densities. These can be further subdivided into the gas giants (Jupiter and Saturn) and the ice giants (Uranus and Neptune) that have large icy cores. Most of our direct information on the composition of the giant"
"density, is one of the largest known solid objects in the Solar System that is less dense than water. Why this should be is not well understood, because objects of its size in the Kuiper belt often contain a fair amount of rock and are hence pretty dense. To have a similar composition to others large KBOs, it would have to be exceptionally porous, which is unlikely given the compactability of water ice. Hence, its density astonished astronomers. The discovery of a minor-planet moon was reported in IAUC 8812 on 22 February 2007. The satellite was detected using the Hubble"
"determine the mass, density, and gravity of the planet. TRAPPIST-1c is the third-largest planet of the TRAPPIST-1 system, with a radius of 1.095 . It is also the most massive of the system as well, with a mass of 1.156 , slightly higher than that of the next most massive, TRAPPIST-1g. Despite its Earth-like mass and radius, TRAPPIST-1c has a lower density (4.89 g/cm) and gravity (0.966g) than Earth. This is consistent with a rock-based composition and a thick, Venus-like atmosphere of water vapor, similar to TRAPPIST-1b. TRAPPIST-1c's atmosphere is expected to be thinner than that of its inner sibling,"
"show evidence of Methane and Acetylene but no Ammonia or Carbon Dioxide. There is currently no explanation why this planet shows strong methane absorption, but the other 3 planets in this system do not, despite all 4 planets having similar atmospheric temperatures. HR 8799 e </math></ref> HR 8799 e is a large exoplanet, orbiting the star HR 8799, which lies 129 lightyears from Earth. This gas giant is between 5 and 10 times the mass of Jupiter, the largest planet in the Solar System. Due to their young age and high temperature all four discovered planets in the HR 8799"
"massive and dense planet could be Kepler-131b, although its density is not as well measured as that of Kepler 10c. The next most massive known solid planets are half this mass: 55 Cancri e and Kepler-20b. Gas planets can have large solid cores. The Saturn-mass planet HD 149026 b has only two-thirds of Saturn's radius, so it may have a rock–ice core of 60 Earth masses or more. Corot-20b has 4.24 times Jupiter's mass but a radius of only 0.84 that of Jupiter; it may have a metal core of 800 Earth masses if the heavy elements are concentrated in"
"its close distance the system is considered an excellent target for studying atmospherics of exoplanets. In late 2017, the masses of all three planets were determined using the Planet Finder Spectrograph on the Magellan II Telescope. Planet b was found to be very iron-rich, planet c appears to be mainly rocky, and planet d is a typical volatile-rich planet. GJ 9827b is noted as being one of the densest planets yet found, with its mass containing about ≥50% iron. More precise radial velocity measurements released in late February 2018 revealed that all three planets have a lower density than Earth"
"as well as composition. The uncompressed density of terrestrial planets trends towards lower values as the distance from the Sun increases. The rocky minor planet Vesta orbiting outside of Mars is less dense than Mars still at, 3.4 g·cm. Calculations to estimate uncompressed density inherently require a model of the planet's structure. Where there have been landers or multiple orbiting spacecraft, these models are constrained by seismological data and also moment of inertia data derived from the spacecraft orbits. Where such data is not available, uncertainties are inevitably higher. It is unknown, whether extrasolar terrestrial planets in general will show"
"LHS 1140 b LHS 1140 b is a massive, dense rocky planet orbiting within the conservative habitable zone of the red dwarf LHS 1140. Discovered in 2017 by the MEarth Project, LHS 1140 b is nearly 7 times the mass of Earth and over 40% larger in radius, putting it within the Super-Earth category of planets. It is one of the densest planets found, with a density over twice that of Earth, along with a high surface gravity of about 3.25g. LHS 1140 b orbits entirely within the star's habitable zone and gets 41% the incident flux of Earth. The"
"the innermost planet in our Solar System, Mercury, takes 88 days to orbit at a distance of 0.38 AU. The eccentricity and inclination of K2-148b's orbit are currently unknown. K2-148b orbits a late-K dwarf star known as K2-148, or EPIC 220194974. It is 63% the radius, 65% the mass, and 10% the luminosity of the Sun, with a temperature of 4079 K and an unknown age. For comparison, the Sun has a temperature of 5778 K and is 4.5 billion years old. It is orbited by a slightly smaller M0.5V red dwarf known as EPIC 220194953 at a distance of"
"naked eye. The binary system is known to host three planets, all larger than Earth with no solid surface. The innermost planet, Kepler-47b, is a gas giant and resides close to its parent stars and therefore is inhospitable to life. It is thought to be smaller than Kepler-47c and is roughly three times the radius of Earth. The second planet, Kepler-47c, is also a gas giant and the outermost planet. It is situated within the habitable zone and its radius is 4 times the Earth's. Although it is assumed Kepler-47c is not capable of harboring life, it is marginally larger"
"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. Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans. The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered"
"between 1.75 and 1.83 Earth radii), the mass is not as well constrained, with a range between 0.9 and 3.3 Earth masses. The mass is determined using transit timing variations of Kepler-11c, and is limited by the quality of the data. Kepler-11b is the closest planet to its host star in the Kepler-11 planetary system. With an estimated density of 1.7 g/cm, comparable to Neptune's, Kepler-11b is denser than the solar system's gas giants but significantly less dense than the terrestrial planets. The estimated density range suggests that it is not of Earth-like composition, yet it is nonetheless composed mostly"
"of the planets in the Solar System, all three would orbit inside that of Venus. The outermost of these three, d, has not yet been confirmed in the HARPS data. A survey with the Spitzer Space Telescope revealed an excess of infrared radiation at a wavelength of 160 μm. This indicated the presence of a debris disk in orbit around the star. This disk was resolved at 70 μm. It was then thought to correspond to an inner radius of 96 AU from the star and outer radius at 195 AU; it is now constrained 30 to over 100 AU."
"southern constellation of Centaurus. , the least massive planet known is PSR B1257+12 A, which is about twice the mass of the Moon. The most massive planet listed on the NASA Exoplanet Archive is DENIS-P J082303.1-491201 b, about 29 times the mass of Jupiter, although according to most definitions of a planet, it is too massive to be a planet and may be a brown dwarf instead. Almost all of the planets detected so far are within the Milky Way, but there have also been a few possible detections of extragalactic planets. The study of planetary habitability also considers a"
"Earth, Kepler-8 is an extremely dim star. It cannot be seen with the naked eye. Kepler-8b is the only planet that has been discovered in the orbit of Kepler-8. With a mass of .603 M and a radius of 1.419 R, the planet is 60% the mass of, but 42% larger than planet Jupiter. The planet is diffuse, with a density of .261 grams/cc, especially in comparison to Jupiter and its density of 5.515 grams/cc. At a distance of .0483 AU, Kepler-8b orbits its star every 3.5225 days. The eccentricity of Kepler-8 is assumed to be 0, which would give"
"appears to the human eye, is 11.39. Therefore, it is far too dim to be seen without a telescope. K2-38b K2-38b, also designated EPIC 204221263 b, is a massive rocky exoplanet closely orbiting a Sun-like star and is one of the densest planets ever found. Discovered in 2016 by Crossfield et al. and later characterized by Sinukoff et al., K2-38b is a rocky Super-Earth about 55% larger than Earth but about 12 times more massive, indicating a composition rich in iron and an extremely high surface gravity. The planet is within K2 Campaign 2, in the constellation Scorpius. K2-38b is"
"define the term ""planet"" formally in 2006, during their 26th General Assembly. That definition excluded Pluto and reclassified it as a dwarf planet. Pluto is the largest and second-most-massive known dwarf planet in the Solar System, and the ninth-largest and tenth-most-massive known object directly orbiting the Sun. It is the largest known trans-Neptunian object by volume but is less massive than Eris. Like other Kuiper belt objects, Pluto is primarily made of ice and rock and is relatively small—about one-sixth the mass of the Moon and one-third its volume. It has a moderately eccentric and inclined orbit during which it"
"years, as opposed to the similarly sized Great Red Spot of Jupiter, which has persisted for centuries. Of all known giant planets in the Solar System, Neptune emits the most internal heat per unit of absorbed sunlight, a ratio of approximately 2.6. Saturn, the next-highest emitter, only has a ratio of about 1.8. Uranus emits the least heat, one-tenth as much as Neptune. It is suspected that this may be related to its extreme 98˚ axial tilt. This causes its seasonal patterns to be very different from those of any other planet in the Solar System. There are still no"
"of Kepler-10b, a rather large confidence interval. Its radius is the second smallest of the six planets discovered in the system at 2.61 times the radius of Earth. Kepler-11f has a density of about 0.7 g/cm, comparable to that of the Solar System's least dense planet, Saturn. Kepler-11f is the fifth planet from Kepler-11, orbiting its host star every 46.68876 days at a distance of 0.25 AU. Its orbital eccentricity is unknown. In comparison, Mercury orbits the Sun every 87.97 days at a distance of 0.387 AU. Kepler-11f has an orbital inclination of 89.4°; it can be seen almost edge-on"
"and liquid matter. It is the largest of the four giant planets in the Solar System and hence its largest planet. It has a diameter of at its equator. The average density of Jupiter, 1.326 g/cm, is the second highest of the giant planets, but lower than those of the four terrestrial planets. Jupiter's upper atmosphere is about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules. A helium atom has about four times as much mass as a hydrogen atom, so the composition changes when described as the proportion of mass contributed by different atoms. Thus, Jupiter's"
"HARPS spectrograph revealed that K2-229b was far denser and more massive than initially expected. The planet has a mass of 2.59 and an extremely high density of about 8.9 g/cm, giving it about 91% more surface gravity than Earth. The unusually high mass and density of K2-229b indicates a Mercury-like composition dominated by an iron core taking up about 70% of the planet's mass. Due to its extremely tight orbit, K2-229b is one of the hottest planets yet found. It has an equilibrium temperature of , hot enough to melt iron. The day side has an even higher temperature in"
"noteworthy that the Earth has the highest density of all the planets in the Solar system; the absorption of the core of the impactor body explains this observation, given the proposed properties of the early Earth and Theia. Comparison of the zinc isotopic composition of Lunar samples with that of Earth and Mars rocks provides further evidence for the impact hypothesis. Zinc is strongly fractionated when volatilized in planetary rocks, but not during normal igneous processes, so zinc abundance and isotopic composition can distinguish the two geological processes. Moon rocks contain more heavy isotopes of zinc, and overall less zinc,"
"dense than lead in order to fit inside its own Hill sphere, or else it will be incapable of supporting an orbit. A spherical geostationary satellite, however, would only need to be more than 6% of the density of water to support satellites of its own. Within the Solar System, the planet with the largest Hill radius is Neptune, with 116 million km, or 0.775 au; its great distance from the Sun amply compensates for its small mass relative to Jupiter (whose own Hill radius measures 53 million km). An asteroid from the asteroid belt will have a Hill sphere"
"Uranus or Neptune. However, the high density of 9.9 g/cm^3 indicates a rocky composition not too different from Earth's albeit with more iron. Without a rocky surface, life may never be able to develop on a planet. Kepler-1652b has a calculated mass of about 7 times that of Earth, which could help power a strong magnetic field. Red dwarfs like Kepler-1652 can produce very strong flares, much more powerful than what the Sun produces, which could erode away the atmosphere of orbiting planets, compromising their habitability. While not all red dwarfs are this active, a strong magnetic field can still"
"style=""background:#a0b0ff;""| Semimajor axis ! align=center style=""background:#a0b0ff;""| Orbital period ! align=center style=""background:#a0b0ff;""| Eccentricity ! align=center style=""background:#a0b0ff;""| Inclination ! align=center style=""background:#a0b0ff;""| Radius Gliese 581e is the innermost planet and, with a minimum mass of 1.7 Earth masses, is the least massive of the three. Discovered in 2009, it is also the most recent confirmed planet to have been discovered in this system. It takes 3.15 days to complete an orbit. Initial analyses suggested that the planet's orbit is quite elliptical but after correcting the radial velocity measurements for stellar activity, the data now indicate a circular orbit. Gliese 581b is the most"
"of Jupiter but due to proximity to its star the planet has expanded to a radius of 1.478 that of Jupiter. Because of this its mean density is only 0.166 g/cm, about the same as expanded polystyrene, a substance used to manufacture lightweight, disposable commercial plastic products. Only WASP-17b (0.49""M""; 1.66""R"") was known to have a lower density at the time of Kepler-7b's discovery. Such low densities are not predicted by current standard theories of planet formation. Kepler-7b orbits its host star every 4.8855 days at a distance of , making it the furthest-orbiting planet of the first five discovered"
"and mass to Earth, with a radius of 1.13 and a mass of 1.66 . It is slightly denser than Earth with 30% more surface gravity, meaning it has a rocky composition. Despite its physical similarities to Earth, it is considered too hot to be habitable, getting 19 times more sunlight due to its 1.6 day orbital period. In April 2017, it was revealed that the planet has an atmosphere, potentially rich in water vapor and methane. Gliese 1132 c was reported by Bonfils et al. using the HARPS spectrograph on the ESO 3.6 m Telescope at the La Silla"