The Big Eye
Published on Oct 21, 2006 at 4:26 pm.
2 Comments.
Filed under telescopes.
I collect stamps. I have since I was a kid. Over the years, my interest has waxed and waned. Eventually, I specialized in US first day covers. Then, I got to where I collected US first day covers about science and space exploration. One of my covers is a 1948 commemorative stamp for the 200 inch Hale Telescope at the Palomar Observatory.
The Hale Telescope was the largest optical telescope in the world for almost four decades. It’s 200 inch diameter mirror is just a bit under 5.1 meters in diameter. Now, that is dwarfed by several telescopes in the 10 meter diameter range. But, the Hale mirror is all one piece, and the others only achieve their titantic size by using mirrors made of a collection of smaller mirrors. The Hale Telescope is not the only instrument at Palomar Observatory, but it is the largest.
The huge mirror weighs over 14 tons by itself. The telescope’s “tube” is composed of a 70 ton open cage of steel beams. The tube is supported in a yoke that is aligned parallel to Earth’s axis of rotation. Slowly turning that yoke allows the telescope to track any object in the sky. It can swing back and forth in the yoke to change the declination that it is pointing. The whole assembly comes in at about 530 tons. Yet, with all of this weight, the thing moves with clockwork precession. Actually, the bearings float on a thin sheet of oil under high pressure.
This telescope, in fact, is so large, that the observer can sit in a “cage” (really a sort of can) at the prime focus of the instrument. Here is a picutre of Edwin Hubble doing just that. Nowadays, cameras and automated instruments can ride in the observing cage.
George Ellery Hale, the telescope’s namesake, never got to see it. Hale secured a $6,000,000 grant to build the telescope in 1928. By the early 1930’s, he had selected Palomar Mountain as the site of the instrument. He felt that San Diego County would be a better location than fast growing Los Angeles County, home to the Mount Wilson Observatory, with its fast growing light pollution. Unfortunately, San Diego County also now is filled with light pollution. Construction of the observatory itself began in 1936, but soon World War II brought a halt to construction. The telescope was not finished until 1948, ten years after Hale had died.
-Astroprof
(Image Credit: Palomar Observatory)
A Ler…-- Rastos de Luz on October 22, 2006 at 4:06 pm: 1
[…] “The Big Eye“, no Astroprof. um pequeno mas interessante artigo sobre o Observatório do Monte Palomar. […]
Astroprof’s Page » Mount Palomar Observatory on August 3, 2007 at 12:31 pm: 2
[…] Most famous among the instruments at Palomar Observatory is the 200-inch Hale Telescope, which was the largest telescope on Earth for close to three decades. However, the Hale Telescope is not the only instrument at Palomar. Palomar is also the home to a 60-inch reflector, a 48-inch Schmidt telescope, and an 18-inch Schmidt camera. The JPL Testbed Interferometer is also at Palomar, as well as the 4-inch Sleuth exoplanet search telescope. […]