Our Solar System has eight planets, a few dwarf planets and more than 200 moons. But wait. Are you seeing double? Or did ...

Add Yahoo as a preferred source to see more of our stories on Google. Dottedhippo/Getty Images On August 24, 2006, our solar system lost a planet. It wasn't by cataclysmic destruction, but rather by ...

Add Yahoo as a preferred source to see more of our stories on Google. An illustration showing Planet Nine, a hypothetical, undiscovered planet in our solar system. New research now suggests the ...

Planet 9 would fall somewhere in between these categories. It could be what is known as a Super-Earth, a rocky planet larger than our own, or a sub-Neptune, a gaseous world less massive and slightly ...

See more of our trusted coverage when you search. Prefer Newsweek on Google to see more of our trusted coverage when you search. A leading scientist has told Newsweek about new evidence supporting the ...

A new study suggests that our solar system’s smallest planet has shrunk by up to 30 percent since its birth roughly 4.5 billion years ago ...

Imagine if the planet Jupiter orbited much closer to the Sun. What effect would a so-called hot Jupiter have on our Solar ...

Forbes contributors publish independent expert analyses and insights. An award-winning reporter writing about stargazing and the night sky. Astronomers have found a distant celestial body — ...

Astronomers have proposed Planet Y, a hypothetical world that could be orbiting unseen in the far reaches of our solar system. Find out more in this short video from EarthSky’s Will Triggs. Is Planet ...

For the first time, astronomers have detected radio signals from a planet beyond our solar system, according to a study available on the preprint server arXiv. The landmark observation offers a new ...

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 ...