Jupiter is the fifth planet from the Sun and the largest planet in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, but is two and a half times that of all the other planets in the Solar System combined. Jupiter is a gas giant, along with Saturn (Uranus and Neptune are ice giants). Jupiter was known to astronomers of ancient times.[11] The Romans named it after their god Jupiter.[12] When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, bright enough to cast shadows,[13] and making it on average the third-brightest object in the night sky after the Moon and Venus.