Planetary-mass Objects
A planetary-mass object, PMO, or planemo is a celestial object with a mass that falls within the range of the definition of a planet: massive enough to achieve hydrostatic equilibrium (to be rounded under its own gravity), but not enough to sustain core fusion like a star. By definition, all planets are planetary-mass objects, but the purpose of the term is to describe objects which do not conform to typical expectations for a planet. These include dwarf planets, the larger moons, free-floating planets not orbiting a star, such as rogue planets ejected from their system, and objects that formed through cloud-collapse rather than accretion (sometimes called sub-brown dwarfs).
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Famous quotes containing the word objects:
“It is an inexpressible Pleasure to know a little of the World, and be of no Character or Significancy in it. To be ever unconcerned, and ever looking on new Objects with an endless Curiosity, is a Delight known only to those who are turned for Speculation: Nay, they who enjoy it, must value things only as they are the Objects of Speculation, without drawing any worldly Advantage to themselves from them, but just as they are what contribute to their Amusement, or the Improvement of the Mind.”
—Richard Steele (1672–1729)