Wednesday, March 19, 2008

Today in History...

In 1915 our favorite ex-planet Pluto was photographed for the first time. It wasn't recognized for what it was, however, until 1930. For years around the turn of the century, astronomers in the States and abroad had been looking for a Planet X out there at the edge of the solar system. Their calculations of the orbit of Uranus didn't seem to jibe with the observable evidence, so they hypothesized that another planet must exist out there, a massive planet with enough gravitational pull to change the orbit of Uranus, throwing off the mathematical calculations.

In 1930, Pluto was finally discovered by Clyde Tombaugh at the Lowell Observatory in Flagstaff, Arizona. Clyde had only just begun to work at the observatory; he was 22 years old. The Lowell Observatory had been central to the search for Planet X since 1905 and was very proud of the achievement, particularly because it brought some positive press to the place which had previously been mired in ridicule due to the fact that the founder, one Percival Lowell, had made repeated and very public comments claiming that the channel-like features visible on the surface of Mars were canals built by an alien race.

There were three names on the short list for the newly-discovered planet, which was named on March 24th, 1930: Minerva, Cronus, and Pluto. Since Minerva was already the name of an asteroid and Cronus had been suggested by a guy at the observatory that everyone hated, Pluto received the unanimous vote.

Of course, it was soon realized that Pluto was nowhere near big enough to have any gravitational pull on the orbit of Uranus. This was further confirmed when it was discovered that part of the mass everyone had assumed was Pluto was actually its moon, Charon. Further attempts were made to find Planet X, but to no avail. Finally, in 1993, data from the Voyager 2 was used to show that astronomers had overestimated the mass of Neptune, throwing off their calculations of Uranus' orbit. No Planet X exists.

In researching this, I was surprised to discover that we currently have a mission on the way to Pluto. The New Horizons spacecraft took off in January of 2006 and should be coming in for a close look at Pluto in July 2015. Ashes of Clyde Tombaugh are on board.
Note: The photo above was taken in September 2006, by the New Horizons spacecraft.

No comments: