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Groups out to the orbit of Earth

• Vulcanoid asteroid
  Vulcanoid asteroid
  
  The vulcanoids are a hypothetical population of asteroids that may orbit the Sun in a dynamically stable zone inside the orbit of the planet Mercury ....
  s are hypothetical asteroids with an aphelion less than 0.4 AU, ie, they orbit entirely within the orbit of Mercury
  Mercury (planet)
  
  Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 88 days. The orbit of Mercury has the highest Orbital eccentricity of all the Solar System planets, and it has the smallest axial tilt....
  . A few searches for Vulcanoids have been conducted but there have been none discovered so far.
• Apohele
  Apohele asteroid
  
  Apohele asteroids are a subclass of Aten asteroids. They have not only their perihelion at less than one astronomical unit , but also their aphelion; that is, their entire orbit is within Earth's....
  s are asteroids whose aphelion is less than 0.983 AU, meaning they orbit entirely within Earth's orbit. "Apohele" is Hawaiian for "orbit". Other proposed names for this group are Inner-Earth Objects or Interior Earth Objects (IEOs) and Anons (as in "Anonymous"). As of March 2008 there are only five known Apoheles with an arc of observations greater than 20 days: (163693) Atira, , , and ; while there are other four possible candidates, but with a too short arc of observations: , , and .
• Mercury-crosser asteroids having a perihelion smaller than Mercury's 0.3075 AU.
• Venus-crosser asteroid
  Venus-crosser asteroid
  
  A Venus-crosser asteroid is an asteroid whose orbit crosses that of Venus. The known numbered Venus-crossers and outer-grazers are listed below ....
  s having a perihelion smaller than Venus
  Venus
  
  Venus is the second-closest planet to the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus , the Roman mythology goddess of love....
  's 0.7184 AU. This group includes the above Mercury-crossers (if their aphelion is greater than Venus's perihelion. All known Mercury crossers satisfy this condition).
• Earth-crosser asteroid
  Earth-crosser asteroid
  
  An Earth-crosser asteroid is a Near-Earth asteroid whose orbit crosses that of Earth. The known numbered Earth-crossers are listed here. Those Earth-crossers whose semimajor axis are smaller than Earth's are Aten asteroids; the remaining ones are Apollo asteroids....
  s having a perihelion smaller than Earth
  Earth
  
  Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
  's 0.9833 AU. This group includes the above Mercury- and Venus-crossers, apart from the Apoheles. They are also divided into the
• Aten asteroid
  Aten asteroid
  
  The Aten asteroids are a group of near-Earth asteroids, named after the first of the group to be discovered . They are defined by having semi-major axis of less than one astronomical unit ....
  s having a semi-major axis
  Semi-major axis
  
  In geometry, the semi-major axis is used to describe the dimensions of ellipses and hyperbolae....
   less than 1 AU, named after 2062 Aten
  2062 Aten
  
  '2062 Aten' is an asteroid that was discovered at the Mount Palomar Observatory by Eleanor F. Helin, who is now the principal scientist for the NEAT project....
  .
• Apollo asteroid
  Apollo asteroid
  
  The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, the first asteroid of this group to be discovered by Karl Wilhelm Reinmuth....
  s having a semi-major axis
  Semi-major axis
  
  In geometry, the semi-major axis is used to describe the dimensions of ellipses and hyperbolae....
   greater than 1 AU, named after 1862 Apollo
  1862 Apollo
  
  1862 Apollo is a Q-type asteroid, discovered by Karl Reinmuth in 1932, but lost and not recovered until 1973. It is named after the Greek god Apollo....
  .
• Arjuna asteroid
  Arjuna asteroid
  
  The Arjuna asteroids are a class of near-Earth asteroids whose orbits are very Earth-like in character, having low inclination, orbital periods close to one Earth year, and low eccentricity ....
  s are somewhat vaguely defined as having orbits similar to Earth's; i.e., with an average orbital radius of around 1 AU and with low eccentricity and inclination. Due to the vagueness of this definition some asteroids belonging to the Apohele
  Apohele asteroid
  
  Apohele asteroids are a subclass of Aten asteroids. They have not only their perihelion at less than one astronomical unit , but also their aphelion; that is, their entire orbit is within Earth's....
  , Amor
  Amor asteroid
  
  The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor. They approach the orbit of the Earth from beyond, but do not cross it....
  , Apollo
  Apollo asteroid
  
  The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, the first asteroid of this group to be discovered by Karl Wilhelm Reinmuth....
   or Aten
  Aten asteroid
  
  The Aten asteroids are a group of near-Earth asteroids, named after the first of the group to be discovered . They are defined by having semi-major axis of less than one astronomical unit ....
   groups can also be classified as Arjunas. The term was introduced by Spacewatch
  Spacewatch
  
  Spacewatch is a project at the University of Arizona that specializes in the study of minor planets, including various types of asteroids and comets....
   and does not refer to an existing asteroid; examples of Arjunas include 1991 VG.
• Earth Trojan
  Earth Trojan asteroid
  
  Earth Trojans are asteroids located in the Earth-Sun Lagrangian points L4 and L5. They are named after the Trojan asteroids that occupy the analogous Lagrangian points of Jupiter ....
  s are asteroids located in the Earth-Sun Lagrangian point
  Lagrangian point
  
  The Lagrangian points , are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects ....
  s L₄ and L₅. Their location in the sky as observed from Earth's surface would be fixed at about 60 degrees east and west of the Sun, and as people tend to search for asteroids at much greater elongations few searches have been done in these locations. No Earth trojans are currently known.
• Near-Earth asteroids is a catch-all group for asteroids whose orbit closely approaches that of Earth. It includes almost all of the above groups, as well as the Amor asteroid
  Amor asteroid
  
  The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor. They approach the orbit of the Earth from beyond, but do not cross it....
  s.

Groups out to the orbit of Mars

• The Amor
  Amor asteroid
  
  The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor. They approach the orbit of the Earth from beyond, but do not cross it....
   asteroids, named after 1221 Amor
  1221 Amor
  
  1221 Amor is the namesake of the Amor asteroids, a group of near-Earth asteroids whose orbits range between those of Earth and Mars . Amors are often Mars-crosser asteroid but they are not Earth-crosser asteroid....
   are Near-Earth asteroids that are not Earth-crossers
  Earth-crosser asteroid
  
  An Earth-crosser asteroid is a Near-Earth asteroid whose orbit crosses that of Earth. The known numbered Earth-crossers are listed here. Those Earth-crossers whose semimajor axis are smaller than Earth's are Aten asteroids; the remaining ones are Apollo asteroids....
  , having a perihelion just outside the Earth's orbit.
• Mars-crosser asteroid
  Mars-crosser asteroid
  
  A Mars-crosser asteroid is an asteroid whose orbit crosses that of Mars. The known numbered Mars-crossers are listed here. They include the two numbered Martian Trojan asteroids: 5261 Eureka and ....
  s have orbits that cross that of Mars, but do not necessarily closely approach the Earth's.
• Mars Trojan
  Mars Trojan asteroid
  
  Mars Trojans are a large group of Trojan that share the orbit of the planet Mars around the Sun. They can be found around the two Lagrangian points 60? ahead and behind of Mars....
  s follow or lead Mars on its orbit, at either of the two Lagrangian point
  Lagrangian point
  
  The Lagrangian points , are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects ....
  s 60° ahead (L₄) or behind (L₅). As of March 2008, four are known. The largest appears to be 5261 Eureka
  5261 Eureka
  
  5261 Eureka was discovered at Palomar Observatory on June 20, 1990 and turned out to be the first known Mars Trojan asteroid. It trails Mars at a distance varying by only 0.3 AU during each revolution ....
  .
• Many of the Earth- Venus- and Mercury-crosser asteroids have aphelia greater than 1AU.

The main asteroid belt

• Inner Main Belt, inside of the strong Kirkwood gap at 2.50 AU due to the 3:1 Jupiter orbital resonance
  Orbital resonance
  
  In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers....
  . The largest member is 4 Vesta
  4 Vesta
  
  4 Vesta is the second most massive object in the asteroid belt, with a mean diameter of about 530 km and an estimated mass of 9% of the mass of the entire asteroid belt....
  .
• It apparently also includes a group called the Main Belt I asteroids which have a mean orbital radius between 2.3 AU and 2.5 AU and an inclination of less than 18°.
• Middle (or intermediate) Main Belt, between the 3:1 and 5:2 Jupiter orbital resonances, the latter at 2.82 AU. The largest member is 1 Ceres. This group is apparently split into the:
• Main Belt IIa asteroids which have a mean orbital radius between 2.5 AU and 2.706 AU and an inclination less than 33°.
• Main Belt IIb asteroids which have a mean orbital radius between 2.706 AU and 2.82 AU and an inclination less than 33°.
• Outer Main Belt between the 5:2 and 2:1 Jupiter orbital resonances. The largest member is 10 Hygiea
  10 Hygiea
  
  '10 Hygiea' is an asteroid located in the main asteroid belt. With somewhat oblong diameters of 350?500 km, and a mass estimated to be 2.9% of the total mass of the belt, it is the List_of_noteworthy_asteroids by volume and mass....
  . This group is apparently split into the:
• Main Belt IIIa asteroids which have a mean orbital radius between 2.82 AU and 3.03 AU, an eccentricity less than .35, and an inclination less than 30°.
• Main Belt IIIb asteroids which have a mean orbital radius between 3.03 AU and 3.27 AU, an eccentricity less than .35, and an inclination less than 30°.

Other groups out to the orbit of Jupiter

• Hungaria asteroids, with a mean orbital radius between 1.78 AU and 2 AU, an eccentricity less than 0.18, and inclination between 16° and 34°. Named after 434 Hungaria
  434 Hungaria
  
  434 Hungaria is a relatively small inner Asteroid belt asteroid. It is classified as an E-type asteroid asteroid. It is the namesake for Hungaria asteroids which orbit the sun on the inside of the 1:4 Kirkwood gap, standing out of the core of the main belt....
  , these are just outside Mars's orbit, and are possibly attracted by the 9:2 resonance.
• Phocaea asteroids, with a mean orbital radius between 2.25 AU and 2.5 AU, an eccentricity greater than 0.1, and inclination between 18° and 32°. Some sources group the Phocaeas asteroids with the Hungarias, but the division between the two groups is real and caused by the 4:1 resonance with Jupiter. Named after 25 Phocaea
  25 Phocaea
  
  '25 Phocaea' is a Main belt asteroid.It was discovered by Jean Chacornac at Marseille, on April 6. 1853. It was his first asteroid discovery....
  .
• Alinda asteroids have a mean orbital radius of 2.5 AU and an eccentricity between 0.4 and 0.65 (approximately). These objects are held by the 3:1 resonance with Jupiter and a 4:1 resonance with Earth
  Earth
  
  Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
  . Many Alinda asteroids have perihelia very close to Earth's orbit and can be difficult to observe for this reason. Alinda asteroids are not in stable orbits and eventually will collide either with Jupiter or terrestrial planets. Named after 887 Alinda
  887 Alinda
  
  '887 Alinda' is an asteroid orbiting the Sun. It was originally discovered by German astronomer Max Wolf in 1918. It lies within the main asteroid belt and is the namesake for the Alinda family group of asteroids, although it is also classified as a Amor_asteroid#Amor_III....
  .
• Pallas family
  Pallas family
  
  The Pallas asteroid family is a grouping of B-type asteroid asteroids at very high inclinations in the intermediate main belt . It was first noted by Kiyotsugu Hirayama in 1928....
   asteroids have a mean orbital radius between 2.7 and 2.8 AU and an inclination between 30° and 38°. Named after 2 Pallas
  2 Pallas
  
  '2 Pallas' is one of the largest asteroids and is located in the main asteroid belt. It was the second asteroid to be discovered, by astronomy Heinrich Wilhelm Matth?us Olbers on March 28, 1802....
  .
• Griqua asteroid
  Griqua family
  
  The Griqua asteroids are a group of asteroids in the Main Belt orbiting the sun between 3.1 and 3.27 astronomical unit. Asteroids in this group have Orbital eccentricity greater than 0.35....
  s have an orbital radius between 3.1 AU and 3.27 AU and an eccentricity greater than 0.35. These asteroids are in stable 2:1 libration
  Libration
  
  In astronomy libration refers to the various orbital conditions which make it possible to see more than 50% of the moon's surface over time, even though the front of the Moon is tidal locking to always face towards Earth....
   with Jupiter, in high-inclination orbits. There are about 5 to 10 of these known so far, with 1362 Griqua
  1362 Griqua
  
  1362 Griqua is a Outer Main-belt Asteroid discovered on July 31, 1935 by Cyril V. Jackson at Union Observatory. It is one of very few asteroids located in the 2 : 1 orbital resonance with Jupiter....
   and 8373 Stephengould
  8373 Stephengould
  
  8373 Stephengould is a Outer Main-belt Asteroid discovered on January 1, 1992 by Carolyn S. Shoemaker and Eugene Merle Shoemaker at Palomar Observatory....
   the most prominent.
• Cybele asteroid
  Cybele asteroid
  
  Cybele asteroids are a group of asteroids in the main belt with a mean orbital radius between 3.27 astronomical unit and 3.7 AU, an Orbital eccentricity less than 0.3, and an inclination less than 25?....
  s have a mean orbital radius between 3.27 AU and 3.7 AU, an eccentricity less than 0.3, and an inclination less than 25°. This group appears to cluster around the 7:4 resonance with Jupiter. Named after 65 Cybele
  65 Cybele
  
  '65 Cybele' is one of the largest asteroids in the main belt. It gives its name to the Cybele asteroids which orbit outward from the Sun from the 2:1 orbital resonance with Jupiter....
  .
• Hilda asteroids have a mean orbital radius between 3.7 AU and 4.2 AU, an eccentricity greater than 0.07, and an inclination less than 20°. These asteroids are in a 3:2 resonance with Jupiter. Named after 153 Hilda
  153 Hilda
  
  153 Hilda is a very large asteroid in the outer Main belt. Because it is composed of primitive carbonaceous chondrites, it has a very dark surface....
  .
• Thule asteroids appear to consist of only one known object, 279 Thule
  279 Thule
  
  279 Thule is a very large Asteroid belt asteroid. It is classified as a D-type asteroid and is probably composed of organic rich silicates, carbon and anhydrous silicates....
  , in a 4:3 resonance with Jupiter.
• Trojan asteroid
  Trojan asteroid
  
  The Jupiter Trojans, commonly called Trojans or Trojan asteroids, are a large group of objects that share the orbit of the planet Jupiter around the Sun....
  s have a mean orbital radius between 5.05 AU and 5.4 AU, and lie in elongated, curved regions around the two Lagrangian point
  Lagrangian point
  
  The Lagrangian points , are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects ....
  s 60° ahead and behind of Jupiter. The leading point, L₄, is called the 'Greek' node and the trailing L₅ point is called the 'Trojan' node, after the two opposing camps of the legendary Trojan War
  Trojan War
  
  In Greek mythology, the Trojan War was waged against the city of Troy by the Achaeans after Paris of Troy stole Helen from her husband Menelaus, the king of Sparta....
  ; with one exception apiece, objects in each node are named for members of that side of the conflict. 617 Patroclus
  617 Patroclus
  
  '617 Patroclus' is a binary asteroid minor planet made up of two similarly-sized objects orbiting their common centre of gravity. It is classified as a Trojan asteroid, sharing an orbit with Jupiter....
   in the Trojan node and 624 Hektor
  624 Hektor
  
  624 Hektor is the largest of the Jupiter Trojan asteroids. It was discovered in 1907 by August Kopff.Hektor is a D-type asteroid, dark and reddish in colour....
   in the Greek node are "misplaced" in the enemy camps.

Groups beyond the orbit of Jupiter

• Damocloid asteroid
  Damocloid asteroid
  
  Damocloids are asteroids such as 5335 Damocles and 1996 PW that have Halley family or long-period highly eccentricity orbits typical of periodic comets such as Comet Halley, but without showing a coma or tail....
  s, also known as the "Oort cloud group," are named after 5335 Damocles
  5335 Damocles
  
  '5335 Damocles' is the archetype of the Damocloid asteroid, asteroids that are inactive nuclei of the Halley Family and long period comets. It was discovered in 1991 and named after Damocles, a figure of Greek mythology....
  . They are defined to be objects that have "fallen in" from the Oort cloud
  Oort cloud
  
  The Oort cloud is a hypothetical spherical cloud of comets which may lie roughly 50 000 astronomical unit, or nearly a light-year, from the Sun....
  , so their aphelia are generally still out past Uranus
  Uranus
  
  Uranus is the seventh planet from the Sun and the third-largest and fourth most massive planet in the Solar System. It is named after the ancient Greek deity of the sky Uranus the father of Kronos and grandfather of Zeus ....
  , but their perihelia are in the inner solar system. They have high eccentricities and sometimes high inclinations, including retrograde orbits. The definition of this group is somewhat fuzzy, and may overlap significantly with comets.
• Centaurs
  Centaur (planetoid)
  
  The centaurs are an unstable orbital class of minor planets named after the mythological race of centaurs. The name was chosen because they behave as half asteroid and half comet....
   have a mean orbital radius roughly between 5.4 AU and 30 AU. They are currently believed to be Trans-Neptunian Object
  Trans-Neptunian object
  
  A trans-Neptunian object is any object in the solar system that orbits the sun at a greater distance on average than Neptune . The Kuiper belt, scattered disk, and Oort cloud are three divisions of this volume of space....
  s that "fell in" after encounters with gas giants. The first of these to be discovered was 2060 Chiron
  2060 Chiron
  
  2060 Chiron is a planetoid in the outer solar system. Discovered in 1977 by Charles T. Kowal , it was the first known member of a new class of objects now known as centaur s, with an orbit between those of Saturn and Uranus ....
  .

Groups at or beyond the orbit of Neptune

• The Neptune Trojans
  NEPTUNE
  
  =Overview=The project, along with sister project, VENUS, offers a unique approach to ocean science. Traditionally, ocean scientists have relied on infrequent ship cruises or space-based satellites to carry out their research....
   currently consist of six objects: , , , , and .
• Trans-Neptunian Object
  Trans-Neptunian object
  
  A trans-Neptunian object is any object in the solar system that orbits the sun at a greater distance on average than Neptune . The Kuiper belt, scattered disk, and Oort cloud are three divisions of this volume of space....
  s (TNOs) are anything with a mean orbital radius greater than 30 AU. This classification includes the Kuiper Belt Objects (KBOs) and the Oort cloud.
• Kuiper Belt Objects extend from roughly 30 AU to 50 AU and are broken into the following subcategories:
• Plutino
  Plutino
  
  In astronomy, a plutino is a trans-Neptunian object in 2:3 orbital resonance with Neptune . For every 2 orbits that a Plutino makes, Neptune orbits 3 times....
  s are KBOs in a 2:3 resonance with Neptune, just like Pluto
  Pluto
  
  Pluto , Minor planet names Pluto, is the second-largest known dwarf planet in the Solar System and the tenth-largest body observed directly orbiting the Sun....
  . The perihelion of such an object tends to be close to Neptune's orbit (much as happens with Pluto), but when the object comes to perihelion, Neptune alternates between being 90 degrees ahead of and 90 degrees behind of the object, so there's no chance of a collision. The MPC defines any object with a mean orbital radius between 39 AU and 40.5 AU to be a plutino. 90482 Orcus
  90482 Orcus
  
  90482 Orcus is a Kuiper Belt object and a likely dwarf planet that was discovered by Michael E. Brown of California Institute of Technology, Chad Trujillo of the Gemini Observatory, and David L....
   and 28978 Ixion
  28978 Ixion
  
  '28978 Ixion' is a Kuiper belt object discovered on May 22, 2001. Ixion is a plutino and a Plutoid candidate; its estimated diameter of 800 km makes it the third largest plutino....
   are among the brightest known.
• Cubewano
  Cubewano
  
  In astronomy a classical Kuiper Belt object, also called a cubewano , is a Kuiper belt object that orbits beyond Neptune and is not controlled by an orbital resonance with the giant planet....
  s, also known as "classical KBOs". They are named after and have a mean orbital radius between approximately 40.5 AU and 47 AU. Cubewanos are objects in the Kuiper belt that didn't get scattered and didn't get locked into a resonance with Neptune. (with two satellites) and are among the brightest.
• Additional groups of resonant objects
  Resonant trans-Neptunian object
  
  In astronomy, a resonant trans-Neptunian object is a trans-Neptunian object in mean motion orbital resonance with Neptune. The orbital periods of the resonant objects are in a simple integer relations with the period of Neptune e.g....
   occupy other orbital resonances with Neptune than the 2:3 resonance of the plutinos and the 1:1 resonance of the Neptune Trojans (such as ), but they have not yet been officially named. There are several known objects in the 1:2 resonance, unofficially dubbed twotinos, with a mean orbital radius of 47.7 AU and an eccentricity of 0.37. There are several objects in the 2:5 resonance (mean orbital radius of 55 AU), and objects in the 4:5, 4:7, 3:5, and 3:4 resonances.
• Scattered Disk Objects (SDOs), unlike cubewanos and resonant objects, typically have highly inclined, high-eccentricity orbits with perihelia that are still not too far from Neptune's orbit.. They are assumed to be objects that encountered Neptune and were "scattered" out of their initial more circular, close to the ecliptic orbits. The recently famous, Pluto-size Eris belongs to this category.
• Extended Scattered Disk (detached) objects
  Detached object (astronomy)
  
  Detached objects are nonclassical trans-Neptunian objects with a perihelion too far away from Neptune to be significantly influenced by it, and so appear to be ?detached? from the solar system....
   with generally highly elliptical, very large orbits of up to a few hundred AU. Their perihelion is too far away from Neptune
  NEPTUNE
  
  =Overview=The project, along with sister project, VENUS, offers a unique approach to ocean science. Traditionally, ocean scientists have relied on infrequent ship cruises or space-based satellites to carry out their research....
   for any significant interaction to occur. One typical member of the extended disk is , while some researchers include Sedna
  90377 Sedna
  
  90377 Sedna is a trans-Neptunian object and a likely dwarf planet, discovered by Michael E. Brown , Chad Trujillo and David L. Rabinowitz on November 14, 2003....
   in this class.
• The Oort cloud
  Oort cloud
  
  The Oort cloud is a hypothetical spherical cloud of comets which may lie roughly 50 000 astronomical unit, or nearly a light-year, from the Sun....
   is a hypothetical cloud of comets with a mean orbital radius between approximately 50,000 AU and 100,000 AU. No Oort cloud objects have been detected, the existence of this classification is only inferred from indirect evidence. Some astronomers have tentatively associated 90377 Sedna
  90377 Sedna
  
  90377 Sedna is a trans-Neptunian object and a likely dwarf planet, discovered by Michael E. Brown , Chad Trujillo and David L. Rabinowitz on November 14, 2003....
   with the Oort cloud.

See also

• Dwarf planet
  Dwarf planet
  
  A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be rounded by its own gravity but has not Clearing the neighbourhood of planetesimals and is not a natural satellite....
  
• List of minor planets
  List of minor planets
  
  This is a list of the lists of small solar system bodies and dwarf planets.* List of minor planets* List of comets* List of trans-Neptunian objects...
  
• Minor Planet Center
  Minor Planet Center
  
  The Minor Planet Center operates at the Smithsonian Astrophysical Observatory , which is part of the Center for Astrophysics along with the Harvard College Observatory ....
  
• Mesoplanet
  Mesoplanet
  
  Mesoplanet is a term coined by Isaac Asimov to refer to Planet with sizes smaller than Mercury but larger than Ceres . Assuming "size" is defined List of solar system objects by radius , mesoplanets should be approximately 1000 km to 5000 km in diameter....