In astronomy, "double planet" and "binary planet" is a binary system where both objects are of planetary mass. Though not an official classification, the European Space Agency has referred to the Earth–Moon system as a double planet. The IAU General Assembly in August 2006 considered a proposal that Pluto and Charon be reclassified as a double planet, but the proposal was abandoned. There are also double minor planets, such as binary asteroids 90 Antiope and binary Kuiper belt objects 79360 Sila–Nunam and . There is debate as to what criteria should be used to distinguish "double planet" from a "planet–moon system". The following are considerations. One important consideration in defining "double planet" is the ratio of the masses of the two bodies. A mass ratio of 1 would indicate bodies of equal mass, and bodies with mass ratios closer to 1 are more attractive to label as "doubles." Using this definition, the satellites of Mars, Jupiter, Saturn, Uranus, and Neptune can all easily be excluded; they all have masses less than 0.00025 of the planets around which they revolve. Some dwarf planets, too, have satellites substantially less massive than the dwarf planets themselves. The most notable exception is the Pluto-Charon system. The Charon-to-Pluto mass ratio of 0.117 is close enough to 1 that Pluto and Charon have frequently been described by many scientists as "double dwarf planets" . The International Astronomical Union currently calls Charon a satellite of Pluto, but has explicitly expressed a willingness to reconsider the bodies double dwarf planets at a future time. Wiz Science™ is "the" learning channel for children and all ages. SUBSCRIBE TODAY Disclaimer: This video is for your information only. The author or publisher does not guarantee the accuracy of the content presented in this video. USE AT YOUR OWN RISK. Background Music: "The Place Inside" by Silent Partner (royalty-free) from YouTube Audio Library. This video uses material/images from https://en.wikipedia.org/wiki/Double+planet, which is released under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . This video is licensed under Creative Commons Attribution-Share-Alike License 3.0 http://creativecommons.org/licenses/by-sa/3.0/ . To reuse/adapt the content in your own work, you must comply with the license terms.

• published: 04 Sep 2015
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