The small world was found during a search for the hypothetical Planet Nine, and astronomers say the next time it will reach ...

U.S. astronomers hunting for "Planet Nine" have instead stumbled on what appears to be a new dwarf planet in the solar system ...

Spotted beyond Neptune, the newly identified object follows an odd path through space, one that complicates a decades-old ...

Simulations show that the stars’ tug could send Mercury, Venus or Mars crashing into Earth — or let Jupiter eject our world from the solar system.

NASA's Perseverance rover is exploring a new Mars region called Krokodillen, which is thought to harbor some of the oldest and most intriguing rocks on the Red Planet.

After surviving the extreme, long-haul journey, you'd next have to navigate all 13 of Uranus' dusty rings - a bit like a spy ...

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the ...

Some astronomers say the strange, clustered orbits of icy rocks beyond Neptune indicate that something big is out there, ...

A new dwarf planet discovery in the outer solar system is challenging the long-standing theory of a hidden giant planet ...

A US-based trio hunting this elusive world has stumbled on what appears to be a new dwarf planet in the solar system's outer ...