Geology of solar terrestrial planets The objects within the Kuiper belt, together with the members of the scattered disc and any potential Hills cloud or Oort cloud objects, are collectively referred to as trans-Neptunian objects (TNOs). Geology of solar terrestrial planets The geology of solar terrestrial planets mainly deals with the geological aspects of the four terrestrial planets of the Solar System – Mercury, Venus, Earth, and Mars – and one terrestrial dwarf planet: Ceres. Earth is the only terrestrial planet known to have an active hydrosphere. Terrestrial planets are substantially different from the giant planets, which might not have solid surfaces and are composed
Climate of Uranus radiates hardly any excess heat at all. The total power radiated by Uranus in the far infrared (i.e. heat) part of the spectrum is times the solar energy absorbed in its atmosphere. In fact, Uranus's heat flux is only W/m², which is lower than the internal heat flux of Earth of about 0.075 W/m². The lowest temperature recorded in Uranus's tropopause is 49 K (−224 °C), making Uranus the coldest planet in the Solar System, colder than Neptune. Another hypothesis states that when Uranus was "knocked over" by the supermassive impactor which caused its extreme axial tilt, the event also