Mercury is bigger than Pluto, but it’s still considered the smallest planet because of Pluto’s designation as a dwarf planet. In 2006, the IAU determined Pluto did not meet the qualifications ...

But Earth isn't the smallest planet in the solar system; that title went to Mercury after Pluto was relegated to a dwarf planet in 2006. But are there even smaller planets out there? And ...

Here's what to know about the short life of what was, for a single human lifetime, the solar system's smallest planet ... to reclassify Pluto as a dwarf planet. The reasoning was that it didn ...

In fact, Ceres makes up 25% of the total mass of the asteroid belt. Still, Ceres remains a dwarf planet. Perhaps as it should, given Pluto's relegation to dwarf planet — Pluto is 14 times larger ...

This planet now orbits a white dwarf, the smaller stellar body that ... “This is definitely the smallest, neatest little rockiest thing we’ve ever found around a white dwarf,” Dr. Mullally ...

Feb. 18 marks the 95th anniversary of the discovery of our outermost planet-not-planet. Here's what to know about the short life of what was, for a single human lifetime, the solar system's smallest ...