It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the edge of our solar system, evading all our efforts to spot it. Some astronomers ...

Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously ...

"It's very rare to discover an object both large and with an exotic orbit." When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. A potential new dwarf ...

After studying thousands of computer simulations of the solar system, researchers at Rice University and the Planetary Science Institute think there’s a 40% chance an elusive “Planet Nine” or “Planet ...

Mercury has long baffled astronomers because it defies much of what we know about planet formation. A new space mission arriving in 2026 might solve the mystery.

In the remote outer reaches of planetary systems, far beyond the orbit of known planets, enormous and mysterious worlds silently loop around their stars. Some drift as far as 10,000 times the distance ...

In the cold, distant reaches of the Solar System, far beyond Pluto, astronomers have just identified what could be a new dwarf planet. It's called 2017 OF 201, a rock that appears to be some 700 ...

Astronomers surveying the outer solar system have revealed that a rare object far beyond Neptune is moving in sync with the eighth planet in an unexpected way. Called 2020 VN40 and first discovered in ...