The long-theorized Planet 9, which astronomers have speculated could be a Neptune-sized planet that has been lurking on the outer edge of the solar system, could explain the unusual clustering and ...

Pluto, which infamously lost its status as the ninth planet in 2006, is less than four billion miles away from the sun, sitting in the Kuiper Belt - a region in our solar system beyond Neptune ...

Astronomers have discovered the earliest seeds of rocky planets forming in the gas around a baby sun-like star, providing a precious peek into the dawn of our own solar system.

In rare find, astronomers identify a planetary sextuplet where six members of the system circle their star in a harmonious pattern with orbital periods that occur in simple, whole-number ratios ...

They say it’s a rare, frozen-in-time cosmic wonder that can help explain how solar systems across the galaxy came to be. The compact in-sync system, announced Wednesday, is 100 light-years away.

This mismatch “doesn’t mean it’s not there, but it means it’s not Planet 9,” Brown said. “I don’t think this planet would have any of the effects on the solar system that we think we ...

Image | Solar System Birth Caption: An image provided by the European Southern Observatory shows HOPS-315, a baby star where astronomers have observed evidence for the earliest stages of planet ...