All of our solar system’s planets are lining up to parade through the night sky at once. This extraordinary celestial event will see the sky scattered with seven visible planets in what is known ...

Analysis of an ancient meteorite suggests that rocky planets both near and distant from the sun may have formed at the same time, challenging current models of our solar system’s evolution.

After a decade-long search, some scientists say a growing number of clues point to the existence of a hidden planet in the Kuiper Belt beyond Neptune — and they may soon have the opportunity to ...

Stars passing close to the sun could cause planets to collide, including with Earth, or even be ejected as rogue planets, new simulations show.