For decades, we believed our Solar System ended with Neptune, followed only by icy debris and distant dwarf planets. But ...

Add Yahoo as a preferred source to see more of our stories on Google. Digital art of distant planet - Dottedhippo/Getty Images On August 24, 2006, our solar system lost a planet. It wasn't 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 ...

Is there a massive undiscovered planet on the outer reaches of the solar system? The idea has been around since before the discovery of Pluto in the 1930s. Labeled as planet X, prominent astronomers ...

Our solar system has two ice giants, Uranus and Neptune, but there may have been a third. According to a new study published in the journal Icarus, this extra world might have triggered a violent ...

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 ...

LONDON — The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper's authors have ...

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 ...