A minor planet is an astronomical object in direct orbit around the Sun that is neither a dominant planet nor originally classified as a comet. Minor planets can be dwarf planets, asteroids, trojans, centaurs, Kuiper belt objects, and other trans-Neptunian objects. The first minor planet discovered was Ceres in 1801 (although from the time of its discovery until 1851 it was considered to be a planet). The orbits of more than 570,000 objects have been archived at the Minor Planet Center.
The term "minor planet" has been used since the 19th century to describe these objects. The term planetoid has also been used, especially for larger objects. Historically, the terms asteroid, minor planet, and planetoid have been more or less synonymous, but the issue has been complicated by the discovery of numerous minor planets beyond the orbit of Jupiter and especially Neptune that are not universally considered asteroids. Minor planets seen outgassing may receive a dual classification as a comet.
Before 2006 the International Astronomical Union had officially used the term minor planet. During its 2006 meeting, the Union reclassified minor planets and comets into dwarf planets and small Solar System bodies. Objects are called dwarf planets if their self-gravity is sufficient to achieve hydrostatic equilibrium, that is, an ellipsoidal shape, with all other minor planets and comets called "small Solar System bodies". The IAU states: "the term 'minor planet' may still be used, but generally the term 'small solar system body' will be preferred." However, for purposes of numbering and naming, the traditional distinction between minor planet and comet is still followed.
Famous quotes containing the words minor and/or planet:
“ChopinTwo embalmers at work upon a minor poet ... the scent of tuberoses ... Autumn rain.”
—H.L. (Henry Lewis)
“Could it not be that just at the moment masculinity has brought us to the brink of nuclear destruction or ecological suicide, women are beginning to rise in response to the Mothers call to save her planet and create instead the next stage of evolution? Can our revolution mean anything else than the reversion of social and economic control to Her representatives among Womankind, and the resumption of Her worship on the face of the Earth? Do we dare demand less?”
—Jane Alpert (b. 1947)