Noun | 1. | ![]() astronomy, uranology - the branch of physics that studies celestial bodies and the universe as a whole biosphere - the regions of the surface and atmosphere of the Earth (or other planet) where living organisms exist celestial body, heavenly body - natural objects visible in the sky inferior planet - any of the planets whose orbit lies inside the earth's orbit gas giant, Jovian planet - any of the four outermost planets in the solar system; much larger than Earth and gaseous in nature (like Jupiter) daystar, morning star, Phosphorus, Lucifer - a planet (usually Venus) seen just before sunrise in the eastern sky outer planet - (astronomy) a major planet whose orbit is outside the asteroid belt (Jupiter, Saturn, Uranus, Neptune, Pluto) solar system - the sun with the celestial bodies that revolve around it in its gravitational field superior planet - any of the planets whose orbit lies outside the earth's orbit terrestrial planet - a planet having a compact rocky surface like the Earth's; the four innermost planets in the solar system |