On February 18th, 1930: Pluto, now a dwarf planet, was discovered

pluto

Being the god of the underworld might not be on top of anyone’s career dreams. But being a celestial orb named after this god may be even worse. That’s the fate of Pluto, a tiny world of ice and rock, once the 9th planet of our solar system – now stripped of its status and remaining a dwarf planet far, far away, circling the sun in a very odd orbit, making a year lasting 248 Earth years.

Since the late 19th century it was suspected that there had to be another planet in our solar system, after the discovery of disturbances in Uranus’ orbit, but it took more than 30 years, till, at last, on February 18th, 1930, Pluto, a dot on a photo plate, was discovered. It was named after the god of the underworld (whose first two letters where, curiously enough, the initials of the man who made it his goal to discover this planet) and became the 9th planet in our system. In 2006, however, the International Astronomical Union (IAU) published a new definition of what a planet had to be like – and Pluto, till then the latest acquisition in our planetary world, met only two of three of the new criteria. And so poor Pluto became the first orb in our solar system that actually LOST the rank of a planet – which made it all the more famous after all.

Celebrate the 83rd anniversary of the discovery of this strange little fellow with a few links:

Here’s a little collection of facts about Pluto. You can also watch a very interesting video about it. Pictures, graphics and explanations are provided here, the pictures Hubble took here and another little collection of pictures here.

Pluto is not easy to deal with – read how difficult it is to map it.

Ever wondered how it would be looking from Pluto to our sun? This computer animation shows it:

This article describes why Pluto is no longer a planet.

A very special treat are these wonderful mails third graders wrote after Pluto lost his planet status, in defense of it. (Huge thanks to my friend Matthias Rascher for pointing me to it.)

In a few years, Pluto will get a visitor from planet Earth – New Horizons, a NASA spacecraft to explore the planet and the Kuyper belt. Learn about it on the NASA website.

But Pluto is not only present in the field of science, but also in the field of fiction, like this article on NBC’s Cosmic Log states.

And, last but not least, if you want to have a really special relationship to Pluto – why not name one of his newly discovered moons? (Here they are, on photos, and also in an article from TIME.)