The term "
Jovian planet" refers to one of 4
gas giants within
Earth's
solar system:
Jupiter,
Saturn,
Uranus, and
Neptune. The term is in reference to the
Roman god Jove, also known as "Jupiter". The term was intended to indicate that the Jovian planets were all similar to Jupiter; but, has become less popular after notable differences were found betwixt these planets; mainly, Jupiter and Saturn are primarily composed of
hydrogen and
helium; while, Uranus and Neptune also have large amounts of
water.
With the discovery of massive extrasolar planets, the term has seen some renewed usage in describing planets of comparable mass to Jupiter.