Everyone's favorite dwarf planet, Pluto, was discovered just 95 years ago. Here's the story of how the once-ninth planet was ...

For the better part of a century, we believed there were nine planets in our solar system, with Pluto being the farthest from the sun. Since the discovery of more Pluto-sized dwarf planets, that ...

Clyde Tombaugh discovered Pluto in 1930 at Lowell Observatory in Flagstaff. Here's how Pluto won - and lost - its planetary status.

A blue atmosphere, smooth areas, and youthful mountain ranges - this dwarf planet is full of surprises. When NASA's New Horizons probe flew past Pluto in July 2015, the images it returned astonished ...

Why was Pluto reclassified as a dwarf planet? One might think that it’s purely a matter of size. Mercury, the smallest of the ...

Arizona in 1930 and was considered our ninth planet until 2006. The International Astronomical Union reclassified Pluto as a dwarf planet because it does not clear its orbit of other debris.

Ganymede, Jupiter's largest moon and the solar system's largest, is bigger than Mercury and the dwarf planet Pluto, with a diameter of 5,268 kilometers.

Forbes contributors publish independent expert analyses and insights. Jamie Carter is an award-winning reporter who covers the night sky.

A New Horizons image of Pluto and its moon Charon revealed more surprises about the dwarf planet and its orbiting moon. Click on the hand to see why Pluto and its moon have shaken things up.

The newly-spotted dwarf planet joins a cohort of other small worlds in that part of space, including Pluto. Together, dwarf planets can help scientists learn a lot about how the solar system ...

For one reason or another, some people are still upset about Pluto's demotion from planet to dwarf planet. This demotion, by the way, occurred all the way back in 2006. So, what does famed ...

Why was Pluto reclassified as a dwarf planet? One might think that it’s purely a matter of size. Mercury, the smallest of the ...