Super Earths exist outside of our solar system
A super-Earth is an extrasolar planet with a mass higher than Earth’s, but substantially below the mass of the Solar System’s smaller gas giants Uranus and Neptune, which are 15 and 17 Earth masses respectively.
The term refers only to the mass of the planet, and does not imply anything about the surface conditions or habitability.
The alternative term “gas dwarfs” may be more accurate for those at the higher end of the mass scale, as suggested by MIT professor Sara Seager, although in actual parlance, mini-Neptunes seems more common.
Theoretical models for super-Earths provide four main possibilities:
* low density super-Earths are inferred to be composed mainly of hydrogen and helium (Mini-Neptunes)
* super-Earths of intermediate density are inferred to either have water as a major constituent (Ocean planets)
* or have a denser core enshrouded with an extended gaseous envelope (Gas dwarf or sub-Neptune)
* A super-Earth of high density is believed to be rocky and/or metallic, like Earth and the other terrestrial planets of the Solar System.