From Mercury's cratered surface to Neptune's deep blue atmosphere, NASA's stunning images reveal the striking beauty and diversity of all eight planets.

But what exactly is a planet? It seems like an easy question. After all, you’re standing on one right now! But the scientific ...

Outer space is, for lack of better words, infinite. For thousands of years, humans have tried to comprehend the vastness of space, and yet so much remains unexplored and undiscovered. While space ...

Our definition of a planet has changed over the years — causing a bit of confusion. | Credit: wasan prunglampoo/Getty Images Over the past 250 years, the number of "planets" in our solar system has ...

If you don’t count Pluto, and the scientific community doesn’t, there are eight planets in this solar system of ours. We know of only one to have life, and we suspect another one might have, at some ...