Pluto hasn't been a planet for almost 20 years. In the early 2000s, scientists discovered several objects of a similar size to Pluto. So, during the summer of 2006, members of the International ...

Earth has a newly-discovered neighbor in the solar system. But the heavenly body – possibly a dwarf planet à la Pluto – isn't a frequent visitor. Located beyond Neptune, its extreme orbit ...

The New Horizons Pluto flyby revealed unexpectedly complex geological features on dwarf planets, prompting further investigation into the diversity within the Kuiper Belt. Several dwarf planets, ...

“My very excellent mother just served us nine.” It doesn’t quite work without “pizzas” at the end. Nor do other schoolchild mnemonics for remembering the planets of the solar system, now that Pluto ...

In 2006, the International Astronomical Union (IAU) voted on the definition of a planet. Famously, Pluto no longer met the criteria and was demoted to a dwarf planet. Things have been a bit of a mess ...

Though the dwarf planet Eris on the edge of the solar system is much denser than Pluto, the two frigid worlds are nearly exactly the same size, a new study finds. Astronomers accurately measured Eris' ...

When it was a planet, Pluto was the Jan Brady of the solar system, always being shunned because of all of the attention a bigger sibling got. ("Mars! Mars! Mars! It's always Mars!") Three years ago ...

NASA's New Horizons spacecraft captured this high-resolution enhanced color view of Pluto that is inserted beneath the Short Wave logo. The image combines blue, red and infrared images taken by the ...