Jupiter is the fifth planet from the sun, and the most massive. In fact, this gas giant is the largest body in the solar system except for the sun itself, and more than two times as massive as all the other planets combined. In composition it closely resembles a star, so much so that some authorities hold that had it been eighty times as massive, it would have become a star. 

Named after the ruler of the Roman gods, Jupiter is large and bright enough to be seen by the naked eye. In fact it is the fourth-brightest object in the night sky, after the Sun, the Moon, and the planet Venus.
