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The definition isn't exactly "cleared its orbit", but rather "gravitationally dominates its orbit". Neptune fits these criteria, because while Pluto does cross
by skykooler 8y ago
The definition isn't exactly "cleared its orbit", but rather "gravitationally dominates its orbit". Neptune fits these criteria, because while Pluto does cross its orbit it is locked in a resonant orbit with Neptune. Similarly, the Moon, as well as Cruithne and several other near-earth objects, are all locked in a resonant orbit with the Earth. However the asteroid belt is not resonant with Ceres.
- garmaine 8y agoAlternatively: Neptune is locked in a resonant orbit with Pluto. Likewise, and even more so for the Earth and Moon, and Pluto and Charon. It's not a quantitatively exact specification.
- Latteland 8y agowhat if the earth was not a moon of another planet but was in an orbital resonance with that larger planet. we'd still not be considered a planet. this planet definition seems pretty arbitrary to me. the astronomy world feels like it's self-defining something to justify pluto not being a planet.