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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 ...

Swipe Down for Full Video Story Most of us learned that the Solar System has eight planets. For many years, Pluto made it ...

James is a published author with multiple pop-history and science books to his name. He specializes in history, space, strange science, and anything out of the ordinary.View full profile James is a ...

About 4.6 billion years ago, a celestial cloud collapsed, paving the way for our solar system to form. Then, a nebula with strong gravitational pull took shape, kick-starting the birth of the sun. But ...

To better understand why the planets have variable compositions, we have to first understand the process of how stars form. While the composition of gas and dust in a precursor molecular cloud is ...

To be a planet, NASA says an object must be big enough that its gravity has cleared away any other objects of a similar size near its orbit around the Sun. I can understand how something can clear ...

Add Yahoo as a preferred source to see more of our stories on Google. Are planets in the solar system that are closer to the Sun older than the ones further away? – Gavriel, age 10, Paducah, Kentucky ...