On the 95th anniversary of its discovery, Pluto remains one of the most beloved and enigmatic worlds in our solar system, whether you call it a planet or not.

Because then, as you decrease the mass of the sun, the mass ratio of Pluto, whatever you want, to the sun becomes a huge number. Then things, even not very massive things start acting like planets.

That’s why the team put an upper bound on mass in their definition of a planet. And in case you’re wondering, Pluto weighs approximately 2.89*10 22 (1.31*10 22 kg).

Pluto was now a double planet: Pluto itself measures about 1,485 miles (2,390 kilometers) across, Charon some 700 miles (1,127 km) across. Like Earth’s Moon, Charon has a large diameter relative ...

We’ve learned that the most common mass/size combination for a planet is intermediate between Venus/Earth and Uranus/Neptune: a class of worlds that was given the name “super-Earth” early on.

Aug. 24, aka #PlutoDemotedDay, is when Pluto became a dwarf planet. For 76 years — from its discovery in 1930 until 2006 — Pluto was considered a planet.

It has now been 15 years since ex-planet Pluto was re-classified as a dwarf planet by the International Astronomical Union (IAU). On August 24, 2006, the IAU convened at its 26th general assembly ...