In the past, scientists thought that the Milky Way has four major "arms" that stretch out around the galaxy.

Astronomers have just discovered a star with a potentially habitable planet that belongs to a string similar to the sun and Earth.

After most planets in the Milky Way formed some four and a half billion years ago, volcanoes erupted on Mars.

The speed of light in a vacuum is 299,792 kilometers per second, and theory shows that nothing can travel faster than light.

Called "The Jewel of the Solar System," Saturn is the only planet whose beautiful rings can be seen from Earth with a telescope.