Astronomers have discovered icy rocks in the outer solar system that appear to defy the laws of physics, sparking speculation ...

For more than a decade, astronomers have chased a planet that no one has ever seen. The case for a hidden ninth planet rests ...

What can rocky planets orbiting in the outer parts of a solar system teach scientists about planetary formation and evolution? This is what a recent study published in Science hopes to address as a ...

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 ...