Eris is three times more distant than Pluto. And its relationship to Pluto — a world demoted since 2006 from the solar system’s ninth planet to a lowly dwarf planet, in large part due to the ...

Pluto isn't alone—it's part of the Kuiper Belt with possibly hundreds of other planet-sized objects. Because Pluto hasn't ...

For decades, Pluto was celebrated as the ninth planet of our solar system. However, in 2006, the International Astronomical ...

The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

And some of them looked awfully similar to Pluto. Then in 2005, astronomers discovered Eris, which estimates at the time suggested was even larger than Pluto. Mike Brown: On January 8 of this year ...

is a disc-shaped region beyond the orbit of Neptune’s in the outer solar system—50 Earth-sun distances—that’s home to dwarf planets like Pluto, Makemake and Eris. It’s also thought to be ...