We've known for over 30 years that there are other stellar systems in our galaxy, but we don't have any idea how many there ...

So exactly how many solar system moons have we found ... "moonlets," also have "fuzzy definitions" and are not considered true moons, Gladman added. Even among recognized moons, there are still ...

For a few evenings around 28 February, every planet in the solar system will be visible in the night sky, thanks to a rare great planetary alignment. Here's how to make sure you don't miss this ...

As well as planets and moons, the solar system also contains dwarf planets, which are too small to be considered planets. The best known of these is Pluto, an ice dwarf that orbits far from the ...