When I was a kid, there were nine planets. Now we know of thousands! But that includes exoplanets, alien worlds that orbit alien suns. Only eight planets call our solar system home. Or there might ...

An artist's rendition of the eight planets in our solar system. The planets are depicted closer together than they really are. NASA / JPL Nearly two decades after Pluto got kicked out of the planet ...

The fact that our solar system has eight planets (unless you’re a Pluto apologist) is one of the first things we learn in our educational journey (anyone remember the “Blue’s Clues” planet song?). But ...

This story is part of Short Wave's series Space Camp about all the weird, wonderful things happening in the universe. Check out the rest of the series. If you were born in the last century you might ...

The Sun is orbited by eight planets, at least five dwarf planets, tens of thousands of asteroids, and around three trillion comets and icy bodies. Although not all objects of the solar system are as ...

The International Astronomical Union defines a planet as a celestial body that orbits the sun, is massive enough that gravity has forced it into a spherical shape, and has cleared away other objects ...

Two years ago the International Astronomical Union (IAU) elected to define the term planet, restricting it to the eight largest bodies orbiting the Sun, and deleting Pluto from the list. The demotion ...

Astronomers are proposing a new, more quantitative definition of what makes a planet. The new definition looks more directly at the object's mass — but it would still leave Pluto out of the running.