Pluto's unusual eccentricity and tilt is likely due to its interactions with neighboring Neptune and other giant planets, ...

Pluto has long been one of the most debated celestial bodies in our solar system. Once classified as the ninth planet, it was ...

The second part of this question is much easier to answer than the first. We will definitely get a different number for Eris’ size once a spacecraft visits it. Spacecraft measurements can be thousands ...

Pluto has just been found to be ever so slightly bigger than we thought, having a diameter of 2,370km. The measurement was made by the New Horizons probe which is just about to flyby the dwarf world.

In a universe full of planets, 2007 OR10 is something special. It’s big, just slightly smaller than the size of Pluto. And it’s close, within our very own solar system. So how did it still manage to ...

Finally, a family portrait of Pluto is beginning to emerge! For the first time ever, astronomers have captured two never-before-photographed moons orbiting Pluto. NASA's New Horizons spacecraft ...

The Hubble Space Telescope may be getting old, but it still has excellent spotting power — witness its discovery of a fourth moon of Pluto, which is between 8 miles and 21 miles in diameter. Says ...

When NASA released images of Pluto in 2015 taken by the New Horizons spacecraft, many were captivated by the dwarf planet’s heart-shaped feature, now called Tombaugh Regio. And now the mystery of how ...

Scientists say they have confirmed that a so-called 10th planet discovered last year is bigger than Pluto, but that likely won't quell the debate over what makes a planet. The astronomers who spotted ...