The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

Gaia-4b is considered a super-Jupiter planet, a relatively cold gas giant, orbiting its star over 570 Earth-days. That star ...

As the gatekeepers to the Kuiper Belt, Charon and Pluto are a unique double dwarf planet system ... Christy had been imaging Pluto with the USNO's 1.5-meter (4.9-foot) telescope.