The simulation of the Solar System that came the closest to the observation was the presence of a small planet, between the ...

The big question is: what exactly did New Horizons spot and discover as it flew through the Pluto System? Today, in the space ...

A new study has proposed the existence of Planet Y, an alternative Planet Nine candidate that is smaller and closer to Earth ...

On August 24, 2006, our solar system lost a planet. It wasn't by cataclysmic destruction, but rather by the vote of the International Astronomical Union, which declared that Pluto, considered the ...

How can we figure out if the planet is actually there? And will it even be bright enough to see? Here are some answers to these and other pressing questions. Others aren’t quite so sure. “I’m very ...

Earlier this year scientists presented evidence for Planet Nine, a Neptune-mass planet in an elliptical orbit 10 times farther from our Sun than Pluto. Since then theorists have puzzled over how this ...

As the world marvels at the first-ever close-up images of Pluto beamed to Earth, it is a reminder of a sharp global division: those with nine-planet childhoods vs. those now growing up in a solar ...

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 ...