Somewhere at the edge of the solar system a new Earth-sized world might be lurking, dubbed Planet Y. Astronomers have long proposed that there might be hidden planets beyond the Kuiper belt, a region ...

Material around Chiron, a small icy world in the far reaches of the solar system, may be taking shape into a ring system of ...

The outer solar system is a vast and mysterious place that could be harboring hidden objects we know almost nothing about — from the elusive Planet Nine and baby black holes to interstellar visitors ...

In humanity’s millennia of staring at the stars and decades of launching probes to explore our universe, only two spacecraft carrying working instruments have ever managed to escape the bubble of ...