Most of these planetary companions are huge gas giants like Jupiter, the largest planet in our solar system. By comparison, our Earth has a Jupiter mass of only 0.003.
Many extrasolar planets have masses far greater than Jupiter.
For example, the planet around the star 70 Virginis in the constellation Virgo, some 60 light-years from Earth, has a mass almost seven times as great as Jupiter. In April 1999, astronomers announced having discovered the first multiple-planet solar system that mimics our own. Upsilon Andromedae is a bright star in the constellation Andromeda visible to the naked eye from the Northern Hemisphere, starting roughly in June. It traverses a circular orbit every 4.6 days and is at least three-quarters of Jupiter's mass. The planet, designated iota Hor b, has an orbital period of 320 days and a mass of at least 2.26 times that of Jupiter.