We just learned about the planet of Mars.
The largest planet in our solar system is Jupiter
(from: wikipedia - jupiter)
Jupiter is called a gas giant because it is mostly made up of gases like air instead of solids or liquids.
It is so big, that it is over 11 times bigger around than earth is!
We only have one moon on the Earth, but Jupiter has 67 moons.
One of them called Ganymede is about half as big as Earth, and bigger than the planet Mercury!
Another interesting thing about Jupiter is something called the Great Red Spot.
It is a giant storm that can be seen on Jupiter's surface.
(from: wikipedia - great red spot)
The spot is over 100 years old, and is so big you could fit more than two whole Earths inside it!
