Mesoplanets are planetary-mass objects with sizes smaller than Mercury but larger than Ceres. The term was coined by Isaac Asimov. Assuming size is defined in relation to equatorial radius, mesoplanets should be approximately 500 km to 2,500 km in radius.
History
The term was coined in Asimov's essay "What's in a Name?", which first appeared in the Los Angeles Times in the late 1980s and was reprinted in his 1990 book Frontiers; the term was later revisited in his essay, "The Incredible Shrinking Planet" which appeared first in The Magazine of Fantasy and Science Fiction and then in the anthology The Relativity of Wrong (1988).
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Today, the known objects that would be included by this definition are Pluto, , , , , , probably , and perhaps . These eight, together with Ceres, are the objects astronomers generally agree are dwarf planets (though with some doubt regarding Orcus).
See also
- Asteroid
- Centaur (minor planet)
- Fusor (astronomy)
- Protoplanet
- Planetesimal
- Brown dwarf