Planet surface of its parent star. The team hypothesized that the planet's magnetosphere was transferring energy onto the star's surface, increasing its already high 7,760 °C temperature by an additional 400 °C. Several planets or dwarf planets in the Solar System (such as Neptune and Pluto) have orbital periods that are in resonance with each other or with smaller bodies (this is also common in satellite systems). All except Mercury and Venus have natural satellites, often called "moons". Earth has one, Mars has two, and the giant planets have numerous moons in complex planetary-type systems. Many moons of the giant planets
Climate of Mars have once had a much thicker and warmer atmosphere, and oceans and/or lakes may have been present. It has, however, proven extremely difficult to construct convincing global climate models for Mars which produce temperatures above 0 °C at any point in its history, although this may simply reflect problems in accurately calibrating such models. Evidence of a geologically recent, extreme ice age on Mars was published in 2016. Just 370,000 years ago, the planet would have appeared more white than red. Mars' temperature and circulation vary every Martian year (as expected for any planet with an atmosphere). Mars lacks oceans,