Astronomers have long speculated about the existence of a mysterious planet lurking far beyond Neptune, a world several times larger than Earth whose gravity could be shaping the outer reaches of our ...

It did not take long for early humans to recognize the differences between the dots of light that shone above them in the night sky. Although it would take some time for humans to understand what ...

A mysterious "rogue planet" has been observed gobbling 6 billion tons of gas and dust a second — an unprecedented rate that blurs the line between planets and stars, astronomers said Thursday. Unlike ...

Does our solar system have a mysterious ninth planet? The discovery of a new dwarf world suggests not. It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is ...

How fast can rogue planets grow? This is what a recent study published in The Astrophysical Journal Letters hopes to address as a team of scientists investigated the discovery of a rogue planet that ...