Happy Anniversary Pluto!

Today is the 75th anniversary of the discovery of the planet Pluto. It was discovered by Clyde Tombaugh working at the Lowell Observatory in Northern Arizona. The observatory had been established by Percival Lowell, who was something of a crackpot outside the scientific establishment. But fortunately, Lowell was also clever enough to invest time and money in a project which will give him lasting fame despite his quirks. It took 25 years of searching at the observatory to find Pluto, and as was already standard in those days in astronomy work at the telescope was just the preliminary for real task of laboring over thousands of photographic slides. A fancy slide viewing device, the blink comparator, was the key piece of equipment that helped find Pluto.

I had the opportunity years ago to take a hands-on look at the early slide collection of a great astronomer of the early 20th century, Harlow Shapley, who ran the observatory at Mt Wilson (at the time the largest in the world) in it's early years. I'm certain that moving on to massively better instruments led Shapley to walk away from the collection I saw, but I couldn't help wonder what treasures were there for someone willing to spend the effort to look through it all.