If you look up at the night sky tonight (June 10) you should be able to see the planet Jupiter.
But if you use a good pair of binoculars or a telescope you will be in for a treat - the space agency NASA says you should also be able to see Jupiter's four largest moons and, if you are really lucky, you will get a glimpse of the banded clouds that surround the planet.
It's because today Jupiter will reach its closest distance to earth for the year.
The planet has 53 named moons but scientists think the real number is 79.
The ones the boffins are most interested in are the first four, the ones you might get to see.
They are known as the Galilean satellites, after the Italian astronomer who first observed them in 1610, Galileo Galilei.
The names of the four moons are Io, Europa, Ganymede, and Callisto. Take a look up the sky tonight and see if you can get to know them better.