January 28, 2013

Photo Essay: Palomar Mountain & Observatory

About a year and a half ago, I decided to spend my first 4th of July weekend as a California resident in San Diego County.

I camped for the first time - in 115 degree heat, commandeered by bees the next morning - and then meandered across San Diego's North County region before visiting the San Diego County Fair and then the Bay for fireworks.

I was sleep deprived from the heat, and the wind storm that hit us overnight, but I took the long way across the county, detouring up Palomar Mountain so I could visit the observatory.

I hadn't posted anything about it until now, but honestly, at the time, I'd been wanting to visit Palomar Observatory way before I'd even heard of Mt. Wilson Observatory. So it's no surprise that, despite my fatigue, I embarked on the steep and winding roads up the mountain to have a look.

The mountain itself consists largely of California state parkland, and the observatory facilities are owned and operated by Caltech.

It is most famous for housing the 200-Inch Hale Telescope...

...the largest effective telescope until 1993, a title it held for 45 years. By the 1930s, light pollution from LA made Mt. Wilson less of an ideal location to study the sky above, so scouting began for a new location for an observatory, in a darker sky community.

At night, the iconic Art Deco dome cranks open, and research of a variety of astronomical studies begin.

Hale's predecessors typically made the mirrors in their telescopes out of fused quartz, but mirror casters were unable to use the same material to manufacture a 200-inch mirror. Hale approached Corning Glass Works in Upstate New York to make one out of a relatively new material at the time: Pyrex.

It took Corning a couple of tries, but they managed to succeed in casting a mirror with the necessary purity and smoothness, and actually far less distortion than the previous 100-inch telescope.

In 1936, Corning sent the giant mirror off on a 16 day journey across the U.S. to Pasadena via train. This precious cargo captured the public's imagination - like our modern day Levitated Mass boulder transport, or the final mission of the Shuttle Endeavour - so much so that crowds lined up along the train tracks to watch the Pyrex passing by, never faster than 25 mph.

In Pasadena, Caltech's optics lab put the finishing touches on the mirror, polishing away nearly 10,000 pounds of glass to create the necessary concave shape. Unfortunately, it's a process that took over a decade to complete, as telescope construction - and the mirror polishing - came to a halt during World War II.

Before it was even fully operational, the Hale Telescope was finally dedicated in 1948, 14 years after the site atop Palomar Mountain was first selected. The next year, full-time studies commence at the observatory, 21 years after Hale first secured a grant for the facility from the Rockefeller Foundation.

And the exploration still continues today! Palomar is actually home to a total of three telescopes, which have been responsible not only for spotting the first brown dwarf star, but also the existence of dwarf planets, initiating the discussions which led to Pluto getting kicked out of the solar system.

Weather permitting, if you can make it up the mountain and through the roads, Palomar Observatory is open to the public for visits and tours. The Reuben H. Fleet Science Center in San Diego's Balboa Park also hosts excursions up the mountain and occasional star parties, which I'd love to go back and do.

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  1. Thanks, nice pictures and well-written commentary. Haven't been to Palomar, yet. One thing Mt. Wilson has over Palomar is that the 60" (and, I am told, soon the 100") telescope(s) are available for rent to the general public. It's not cheap, but if you can get enough friends together, it's not a bad way to spend an evening. One of these days, I'm going to have to splurge for that.