Subsatellite

Not to be confused with Subsatellite point.
Artist's concept of exomoon Kepler-1625b I orbiting exoplanet Kepler-1625b. Kepler-1625b I could theoretically have a subsatellite itself.[1][2]

A subsatellite, also known as a submoon or a moonmoon, is a "moon of a moon" or a hypothetical natural satellite that orbits the moon of a planet.[3]

It is inferred from the empirical study of natural satellites in the Solar System that subsatellites may be rare, albeit possible, elements of planetary systems. In the Solar System, the giant planets have large collections of natural satellites. The majority of detected exoplanets are giant planets; at least one, Kepler-1625b, may have a very large exomoon, named Kepler-1625b I, which could theoretically host a subsatellite.[1][2][4][5] Nonetheless, aside from human-launched satellites in temporary lunar orbit, no notable subsatellite is known in the Solar System or beyond. In most cases, the tidal effects of the planet would make such a system unstable.

  1. ^ a b Forgan, Duncan (4 October 2018). "The habitable zone for Earthlike exomoons orbiting Kepler-1625b". arXiv:1810.02712v1 [astro-ph.EP].
  2. ^ a b Chou, Felcia; Villard, Ray; Hawkes, Alison (3 October 2018). Brown, Katherine (ed.). "Astronomers Find First Evidence of Possible Moon Outside Our Solar System". Solar System and Beyond (Press release). NASA. Retrieved 11 October 2018.
  3. ^ "Where is Earth's submoon?". phys.org. Retrieved 2020-10-13.
  4. ^ Drake, Nadia (3 October 2018). "Weird giant may be the first known alien moon - Evidence is mounting that a world the size of Neptune could be orbiting a giant planet far, far away". National Geographic Society. Archived from the original on October 3, 2018. Retrieved 11 October 2018.
  5. ^ "Hubble finds compelling evidence for a moon outside the Solar System". Hubble Space Telescope. 3 October 2018. Retrieved 11 October 2018.