A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below the mass of the Solar System's ice giants Uranus and Neptune, which are 15 and 17 Earth masses respectively. The term super-Earth 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 mini-Neptunes is more common.