Pluto, not to be confused with Micky Mouse’s dog, is going to be in the news a lot soon, as we are finally going to take a closer look to the elusive dwarf planet.
Discovered by Clyde Tombaugh on the 18th of February 1930, it is smaller than our Moon with a 1184 Km radius, versus our moon’s 1736 km radius, and lighter since it has only 18% the mass of our satellite. The surface area of Pluto is smaller than Russia.
It takes over 247 years to go around the Sun. Due to its highly eccentric orbit from 1979 until 1999 Pluto was closer to the Sun than Neptune. Pluto is currently about 4 and a half light hours away from Earth, or 4.7 billion kilometres.
Pluto has 5 moons all named after Greco-Roman features and inhabitants of the underworld: Charon, Styx, Nix, Kerberos, and Hydra. Hydra is not a Tartarus creature per se, but it’s 9 heads were taken as a symbol for Pluto’s tenure as the 9th Planet.
Pluto & Charon form a unique and interesting system in that they have a case of mutual tidal locking: they both show the same face to each other. Also, Charon doesn’t orbit around Pluto. They form a binary system orbiting a barycentre about 1000km over the surface of Pluto. This is not at all unusual. Jupiter and the Sun orbit a centre of mass over the surface of the sun, and in just over 100 million of years the Earth-Moon system will become a binary system as well, as the moon moves away from us.
As I previously discussed in a vlog, Pluto is not considered a planet anymore but a dwarf planet. The term was adopted by the International Astronomical Union in 2006, and plenty of chaos erupted as a result of this.
The reason for the reclassification is the discovery of Eris, a transneptunian object bigger than Pluto. The discoverer, American Astronomer Mike Brown, has won the internet by adopting the twitter handle @plutokiller.
The definition of what makes a planet is far from perfect since, for example, it excludes every exoplanet from the planetary status, but it is what we have to work with at the moment.