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This article includes a list of the most massive known objects of the Solar System and partial lists of smaller objects by observed mean radius. These lists can be sorted according to an object's radius and mass and, for the most massive objects, volume, density, and surface gravity, if these values are available. These lists contain the
Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
, the
planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a yo ...
s,
dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to p ...
s, many of the larger
small Solar System bodies A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite. The term was first defined in 2006 by the International Astronomical Union (IAU) as follows: "All other objects, ...
(which includes the
asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere ...
s), all named
natural satellite A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are often colloquially referred to as ''moo ...
s, and a number of smaller objects of historical or scientific interest, such as
comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...
s and
near-Earth object A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3  astronomical units (AU) ...
s. Many trans-Neptunian objects (TNOs) have been discovered; in many cases their positions in this list are approximate, as there is frequently a large uncertainty in their estimated diameters due to their distance from Earth.
Solar System The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
objects more massive than 1021
kilogram The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquiall ...
s are known or expected to be approximately spherical. Astronomical bodies relax into rounded shapes (
spheroid A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters. A spheroid has c ...
s), achieving
hydrostatic equilibrium In fluid mechanics, hydrostatic equilibrium (hydrostatic balance, hydrostasy) is the condition of a fluid or plastic solid at rest, which occurs when external forces, such as gravity, are balanced by a pressure-gradient force. In the planeta ...
, when their own gravity is sufficient to overcome the structural strength of their material. It was believed that the cutoff for round objects is somewhere between 100 km and 200 km in radius if they have a large amount of ice in their makeup; however, later studies revealed that icy satellites as large as
Iapetus In Greek mythology, Iapetus (; ; grc, Ἰαπετός, Iapetós), also Japetus, is a Titan, the son of Uranus and Gaia and father of Atlas, Prometheus, Epimetheus, and Menoetius. He was also called the father of Buphagus and Anchiale in other ...
(1,470 kilometers in diameter) are not in hydrostatic equilibrium at this time, and a 2019 assessment suggests that many TNOs in the size range of 400–1000 kilometers may not even be fully solid bodies, much less gravitationally rounded. Objects that are ellipsoids due to their own gravity are here generally referred to as being "round", whether or not they are actually in equilibrium today, while objects that are clearly not ellipsoidal are referred to as being "irregular." Spheroidal bodies typically have some polar flattening due to the
centrifugal force In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis which is parallel ...
from their rotation, and can sometimes even have quite different equatorial diameters (scalene
ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface;  that is, a surface that may be defined as the z ...
s such as ). Unlike bodies such as Haumea, the irregular bodies have a significantly non-ellipsoidal profile, often with sharp edges. There can be difficulty in determining the diameter (within a factor of about 2) for typical objects beyond Saturn. (See
2060 Chiron 2060 Chiron is a small Solar System body in the outer Solar System, orbiting the Sun between Saturn and Uranus. Discovered in 1977 by Charles Kowal, it was the first-identified member of a new class of objects now known as centaurs—bodies o ...
as an example) For TNOs there is some confidence in the diameters, but for non-binary TNOs there is no real confidence in the masses/densities. Many TNOs are often just assumed to have Pluto's density of 2.0 g/cm3, but it is just as likely that they have a comet-like density of only 0.5 g/cm3. For example, if a TNO is incorrectly assumed to have a mass of 3.59 kg based on a radius of 350 km with a density of 2 g/cm3 but is later discovered to have a radius of only 175 km with a density of 0.5 g/cm3, its true mass would be only 1.12 kg. The sizes and masses of many of the moons of Jupiter and Saturn are fairly well known due to numerous observations and interactions of the ''
Galileo Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He was ...
'' and '' Cassini'' orbiters; however, many of the moons with a radius less than ~100 km, such as Jupiter's Himalia, have far less certain masses. Further out from Saturn, the sizes and masses of objects are less clear. There has not yet been an orbiter around Uranus or Neptune for long-term study of their moons. For the small outer
irregular moon In astronomy, an irregular moon, irregular satellite or irregular natural satellite is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit. They have been captured by their parent planet, unlike regular s ...
s of Uranus, such as
Sycorax Sycorax is an unseen character in William Shakespeare's play '' The Tempest'' (1611). She is a vicious and powerful witch and the mother of Caliban, one of the few native inhabitants of the island on which Prospero, the hero of the play, is s ...
, which were not discovered by the ''
Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, to study the outer planets and interstellar space beyond the Sun's heliosphere. As a part of the Voyager program, it was launched 16 days before its twin, '' Voyager 1'', on ...
'' flyby, even different NASA web pages, such as the National Space Science Data Center and JPL Solar System Dynamics, give somewhat contradictory size and
albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...
estimates depending on which research paper is being cited. There are uncertainties in the figures for mass and radius, and irregularities in the shape and density, with accuracy often depending on how close the object is to Earth or whether it has been visited by a probe.


Graphical overview

File:Solar-system-top50-diameter.svg, Relative diameters of the fifty largest bodies in the Solar System, colored by orbital region. Values are diameters in kilometers. Scale is linear. File:Sun vs planets en.svg, Relative masses of the bodies of the Solar System. Objects smaller than
Saturn 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 of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
are not visible at this scale. File:Masses of the planets en.svg, Relative masses of the Solar planets.
Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...
at 71% of the total and
Saturn 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 of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
at 21% dominate the system. File:Masses of Solid Solar System bodies en.svg, Relative masses of the solid bodies of the Solar System.
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
at 48% and
Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...
at 39% dominate. Bodies less massive than
Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest k ...
are not visible at this scale. File:Masses of all moons.png, Relative masses of the rounded moons of the Solar System. Mimas,
Enceladus Enceladus is the sixth-largest moon of Saturn (19th largest in the Solar System). It is about in diameter, about a tenth of that of Saturn's largest moon, Titan. Enceladus is mostly covered by fresh, clean ice, making it one of the most refle ...
, and Miranda are too small to be visible at this scale.


Objects with radius over 400 km

The following objects have a mean radius of at least 400 km. It was once expected that any icy body larger than approximately 200 km in radius was likely to be in
hydrostatic equilibrium In fluid mechanics, hydrostatic equilibrium (hydrostatic balance, hydrostasy) is the condition of a fluid or plastic solid at rest, which occurs when external forces, such as gravity, are balanced by a pressure-gradient force. In the planeta ...
(HE). However, (r = 470 km) is the smallest body for which detailed measurements are consistent with hydrostatic equilibrium, whereas
Iapetus In Greek mythology, Iapetus (; ; grc, Ἰαπετός, Iapetós), also Japetus, is a Titan, the son of Uranus and Gaia and father of Atlas, Prometheus, Epimetheus, and Menoetius. He was also called the father of Buphagus and Anchiale in other ...
(r = 735 km) is the largest icy body that has been found to not be in hydrostatic equilibrium. The known icy moons in this range are all ellipsoidal (except
Proteus In Greek mythology, Proteus (; Ancient Greek: Πρωτεύς, ''Prōteus'') is an early prophetic sea-god or god of rivers and oceanic bodies of water, one of several deities whom Homer calls the "Old Man of the Sea" ''(hálios gérôn)'' ...
), but trans-Neptunian objects up to 450–500 km radius may be quite porous. For simplicity and comparative purposes, the values are manually calculated assuming that the bodies are all spheres. The size of solid bodies does not include an object's atmosphere. For example, Titan looks bigger than Ganymede, but its solid body is smaller. For the
giant planet The giant planets constitute a diverse type of planet much larger than Earth. They are usually primarily composed of low-boiling-point materials ( volatiles), rather than rock or other solid matter, but massive solid planets can also exist. T ...
s, the "radius" is defined as the distance from the center at which the atmosphere reaches 1 bar of atmospheric pressure.


Smaller objects by mean radius


From 200 to 399 km

All imaged icy moons with radii greater than 200 km except
Proteus In Greek mythology, Proteus (; Ancient Greek: Πρωτεύς, ''Prōteus'') is an early prophetic sea-god or god of rivers and oceanic bodies of water, one of several deities whom Homer calls the "Old Man of the Sea" ''(hálios gérôn)'' ...
are clearly round, although those under 400 km that have had their shapes carefully measured are not in hydrostatic equilibrium. The known densities of TNOs in this size range are remarkably low (), implying that the objects retain significant internal porosity from their formation and were never gravitationally compressed into fully solid bodies.


From 100 to 199 km

This list contains a selection of objects estimated to be between 100 and 199 km in radius (200 and 399 km in diameter). The largest of these may have a hydrostatic-equilibrium shape, but most are irregular. Most of the trans-Neptunian objects (TNOs) listed with a radius smaller than 200 km have "''assumed sizes'' based on a ''generic''
albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...
of 0.09" since they are too far away to directly measure their sizes with existing instruments. Mass switches from 1021 kg to 1018 kg (Zg).
Main-belt asteroid The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...
s have orbital elements constrained by (2.0 AU < a < 3.2 AU; q > 1.666 AU) according to JPL Solar System Dynamics (JPLSSD). Many TNOs are omitted from this list as their sizes are poorly known.


From 50 to 99 km

This list contains a selection of objects 50 and 99 km in radius (100 km to 199 km in average diameter). The listed objects currently include most objects in the
asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...
and moons of the
giant planet The giant planets constitute a diverse type of planet much larger than Earth. They are usually primarily composed of low-boiling-point materials ( volatiles), rather than rock or other solid matter, but massive solid planets can also exist. T ...
s in this size range, but many newly discovered objects in the outer Solar System are missing, such as those included in the following reference.
Asteroid spectral types An asteroid spectral type is assigned to asteroids based on their emission spectrum, color, and sometimes albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not internally differentiated ...
are mostly Tholen, but some might be SMASS.


From 20 to 49 km

This list includes few examples since there are about 589
asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere ...
s in the
asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...
with a measured radius between 20 and 49 km. Many thousands of objects of this size range have yet to be discovered in the trans-Neptunian region. The number of digits is not an endorsement of
significant figures Significant figures (also known as the significant digits, ''precision'' or ''resolution'') of a number in positional notation are digits in the number that are reliable and necessary to indicate the quantity of something. If a number expres ...
. The table switches from  kg to  kg ( Eg). Most mass values of asteroids are assumed.


From 1 to 19 km

This list contains some examples of Solar System objects between 1 and 19 km in radius. This is a common size for asteroids, comets and irregular moons.


Below 1 km

This list contains examples of objects below 1 km in radius. That means that irregular bodies can have a longer chord in some directions, hence the mean radius averages out. In the
asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...
alone there are estimated to be between 1.1 and 1.9 million objects with a radius ''above'' 0.5 km, many of which are in the range 0.5–1.0 km. Countless more have a radius ''below'' 0.5 km. Very few objects in this size range have been explored or even imaged. The exceptions are objects that have been visited by a probe, or have passed close enough to Earth to be imaged. Radius is by mean geometric radius. Number of digits not an endorsement of
significant figures Significant figures (also known as the significant digits, ''precision'' or ''resolution'') of a number in positional notation are digits in the number that are reliable and necessary to indicate the quantity of something. If a number expres ...
. Mass scale shifts from × 1015 to 109 kg, which is equivalent to one billion kg or 1012 grams (
Teragram The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially. ...
– Tg). Currently most of the objects of mass between 109 kg to 1012 kg (less than 1000 teragrams (Tg)) listed here are
near-Earth asteroid A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU) ...
s (NEAs). The Aten asteroid has less mass than the
Great Pyramid of Giza The Great Pyramid of Giza is the biggest Egyptian pyramids, Egyptian pyramid and the tomb of Fourth Dynasty of Egypt, Fourth Dynasty pharaoh Khufu. Built in the early 26th century BC during a period of around 27 years, the pyramid is the oldes ...
, 5.9 × 109 kg. For more about very small objects in the Solar System, see
meteoroid A meteoroid () is a small rocky or metallic body in outer space. Meteoroids are defined as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than this are classified as mic ...
,
micrometeoroid A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through Earth's atmosphere and reaches Earth's surface. The term "micrometeoro ...
,
cosmic dust Cosmic dust, also called extraterrestrial dust, star dust or space dust, is dust which exists in outer space, or has fallen on Earth. Most cosmic dust particles measure between a few molecules and 0.1 mm (100 micrometers). Larger particles ar ...
, and
interplanetary dust cloud The interplanetary dust cloud, or zodiacal cloud (as the source of the zodiacal light), consists of cosmic dust (small particles floating in outer space) that pervades the space between planets within planetary systems, such as the Solar Syste ...
. ''(See also Visited/imaged bodies.)''


Gallery


See also

*
List of gravitationally rounded objects of the Solar System This is a list of most likely gravitationally rounded objects of the Solar System, which are objects that have a rounded, ellipsoidal shape due to their own gravity (but are not necessarily in hydrostatic equilibrium). Apart from the Sun itself, ...
*
List of dwarf planets The number of dwarf planets in the Solar System is unknown. Estimates have run as high as 200 in the Kuiper belt and over 10,000 in the region beyond. However, consideration of the surprisingly low densities of many large trans-Neptunian objects ...
*
List of minor planets The following is a list of numbered minor planets in ascending numerical order. With the exception of comets, minor planets are all small bodies in the Solar System, including asteroids, distant objects and dwarf planets. The catalog consists ...
*
List of natural satellites The Solar System's planets, and its most likely dwarf planets, are known to be orbited by at least 221 natural satellites, or moons. At least 20 of them are large enough to be gravitationally rounded; of these, all are covered by a crust of ...
*
List of near-Earth asteroids by distance from Sun This list contains many notable near-Earth asteroids organised by their average distance from the Sun, and includes the planets A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory ...
*
List of Solar System objects most distant from the Sun These Solar System minor planets are the furthest from the Sun . The objects have been categorized by their approximate current distance from the Sun, and not by the calculated aphelion of their orbit. The list changes over time because the obj ...
* List of space telescopes *
Lists of astronomical objects This is a list of lists, grouped by type of astronomical object. Solar System * List of Solar System objects * List of gravitationally rounded objects of the Solar System * List of Solar System objects most distant from the Sun * List of So ...


Notes


References


Further reading


NASA Planetary Data System (PDS)



Minor Planet discovery circumstances
* Supplemental IRAS Minor Planet Survey (SIMPS) and IRAS Minor Planet Survey (IMPS) *
V6additionalfrom here
*
Asteroid Data Archive Archive
''Planetary Science Institute''


External links





{{DEFAULTSORT:List Of Solar System Objects By Size
Size Size in general is the magnitude or dimensions of a thing. More specifically, ''geometrical size'' (or ''spatial size'') can refer to linear dimensions (length, width, height, diameter, perimeter), area, or volume. Size can also be meas ...