The fifth planet from the Sun, Jupiter, is a giant gas planet with a thick atmosphere of hydrogen and helium. It has colorful cloud bands and the famous Great Red Spot, a massive storm that has rumbled for 350 years.
It’s also 11 times as large as Earth, so it could hold more than 1,300 of our planets. And it has such a high density, that astronomers say it may be able to support rocky planets inside.
Jupiter is part of the group of planets called the gas giants (along with Saturn, Uranus and Neptune). They are bigger in size than terrestrial or telluric planets like Mercury, Venus, Earth and Mars, but they have lower densities. Jupiter has a thin atmosphere, mostly made of hydrogen and helium, but it may have a rocky core.
Astronomers have spotted a record-setting fifth planet orbiting the sunlike star 55 Cancri, 41 light-years away in the constellation Cancer. It’s a mini-Saturn, with about 46 Earth masses, and lies fourth out from the star, in the zone where liquid water might exist.
A number of theories have been proposed about the Fifth Planet, which some call Nibiru or Tyche and others nickname Planet Nine. One idea is that it was a giant ice-giant, similar to Neptune and Uranus, ejected by the gravitational pull of Jupiter and Saturn around 4 billion years ago. Another is that it’s a rogue planet that’s still out there in the Milky Way and hasn’t been found yet.