Wednesday, June 22, 2011

The Mt. Wilson Observatory: Einstein Was Here!

Continuing from the last blog about the solar telescope...

I mentioned last time that when the observatory was founded in 1904 until 1919 it was known as the Mt. Wilson Solar Observatory. During that time there were three major solar telescopes here: The Snow Solar Telescope, The 60-Foot Solar Tower, and the 150-Foot one I showed some of last time. The solar was dropped from the observatory name in 1919.

I continued walking for a few minutes and passed by the dome of the 60-inch telescope dome. It is a reflecting telescope with a 60-inch diameter mirror. This telescope was completed in 1908 and was the biggest in the world at the time until replaced by a bigger one at this observatory. It is the only telescope at Mt. Wilson the general public can use for a fee.
In 1916, Harlow Shapley used the scope to determine that the M13 gobular cluster of stars is 36,000 light years from us. This showed that the Milky Way Galaxy we reside in was quite large. At that time, since they were still trying to figure out how to gage distances, it was believed that our galaxy was the only one out there. We'll get to some of the historical debate on this in the next blog. One thing to add on this is that Shapley assumed that M13 was closer to the center of the galaxy, while our sun and the earth were far away from the center. We now know this to be true.
In the above picture, the 60-inch dome is off behind the trees to the right side of the picture. The little building to the left is the "galley" where astronomers could make their meals, drink coffee or tea...more on this in a moment. However, notice that little drinking fountain next to the short stairs! I was so relieved to see that. It was so cold, and I made sure my water bottles were filled up for the hike down. I knew I would be okay going down now. See the little dome in the distance? Notice the pipes running from it to the right side of the picture? Those same pipes are in the picture below. This is just part of the CHARA (Center for High Angular Resolution Astonomy) Array. Spread throughout Mt. Wilson in a Y-formation are a total of six domes each with a telescope. Each scope has a one meter (3+ feet) diameter mirror that captures light, the light is transported through the pipes, and sent to the central Beam Combining Lab. Computers are involved lining up all the mirrors to combine with each other. This allows the Array to see as if it were a single telescope about 400 meters in diameter. It can see the fine details in stars and star systems. The concerns with CHARA are the issues of star diameters, shapes, surface tempatures, masses, distances, and luminosities. The pamphlet I got from there says it is the structural equivalent of seeing a nickel 10,000 miles away which totally blows my mind. It is run by Georgia State University. BTW, there are a bunch of universities that use the equipment at Mt. Wilson. Each doing their own projects. Here is a picture of Albert Einstein and others when he visited Mt. Wilson. In the above picture where I was at the "galley" with the drinking fountain, you just turn around and there is a bridge that takes you to the 100-inch dome. the picture below is really close to where he would have been, and there is a little plaque that notes this with above picture. They have more trees around, the bridge has changed a little, but this is where he was standing. There is another picture out there of Edwin Hubble on this same bridge at this point. Hubble will be discussed in the next blog. The deal was that George Hale was very strict about where the astronomers could make and eat their food. The risk of fire destroying the telescopes, equipment, and the whole observatory was and is still a concern. Fortunately, this did not happen during the Station Fire a few years back, but they do have large water tanks on reserve for fighting fires at Mt. Wilson. That is why Hale set up the galley and other places for astronomers to eat and prepare food.
In the next blog I will cover the 100-inch telescope that revolutioned astronomy by showing our place in the universe in the early to mid-20th century. Unlike, the other domes, we actually get to view the whole telescope through a window.

Einstein Was Here! (Youtube Version)

Einstein Was Here! (Vimeo Version)

The Chara Array website (Georgia State University)