The International Astronomical Union has just released the official book of the International Year of Astronomy. Eyes on the Skies: 400 Years of Telescopic Discovery celebrates the history of the telescope and what we have learned about our universe since Galileo first lined up two lenses in a narrow tube. The book comes with a one-hour DVD on the history of the telescope, but one can also download and view the whole show at the Hubble Information Centre.
I saw a replica of Galileo’s telescope last weekend at the center of the universe, I mean, the Centre of the Universe, the interpretive centre at my local astronomical observatory, which was having a special IYA open house. It is really quite remarkable what Galileo was able to observe with an instrument that would today be considered crude and limited. More modern telescopes were on display outside, pointed at Venus. Yes, Venus was visible in the middle of the afternoon, and when I looked through one of the eyepieces I saw that it was half-full! It had not occurred to me that planets have phases just like the moon, but of course they do. I had just never seen them as anything other than points of light before.
The astronomical delights continued with a lecture on the ancient history of astronomy, from the Greeks to Galileo. We learned about how the Greeks calculated the size of the Earth, Sun and Moon, and the distances between them, without any equipment other than their eyes and brains, and even without a reliable way to measure distance. Eratosthenes based his calculation of the size of the Earth on the number of camel-days between two cities, and came within 1% of the actual figure. They all assumed that the Earth was round, but they couldn’t accept the notion that it was spinning because if it was, anything that wasn’t nailed down would go flying off into space. So they devised complicated schemes to explain the “wandering” of the planets (“planet”comes from the Greek for “wandering star”), giving rise to such complex timekeepers as the Antikythera mechanism.
After the talk we crossed the parking lot to tour the 1.83m Plaskett telescope, which was the largest telescope yet made when it was installed here in 1918. We were met by a fellow in a toque and gloves and soon found out why. The building is refrigerated so that when they open the roof the view of the stars is not distorted by rising heat waves. The astronomers have a heated office to retreat to, so they don’t have to spend their winter nights in the cold. In fact they make all their observations in the office—the telescope no longer has an eyepiece, just an electronic optical sensor and a spectrograph.
It was quite an exciting, and somewhat vertiginous, moment when they opened the sky doors and rotated the telescope for us. The telescope and the roof are designed to move together so everything rotates at once and if you’re not hanging on to something it can really make your head spin! Though the Plaskett telescope is now considered small by world standards, the astronomers there have gained an international reputation for devising means to correct distortions and extract the great possible amount of data from optical telescopes. According to the website, the telescope is now 10,000 times more sensitive than when it was first built!
As I was leaving I noticed a wooden tub and what looked like a boiler, which turned out to be equipment used in the resurfacing of the mirror. First they immerse it in a solution that removes the old coating, then they place the mirror in a vaccuum chamber and release aluminum particles which then stick to the base and create a perfect mirror finish. It struck me that science is the ultimate DIY project. If you build and use it, you also have to be able to maintain and fix it, because you can’t send a two ton piece of precision-ground glass out for polishing every few months.
That completed my tour of the Centre of the Universe, and my first “EVA” for the Astronomy Reading Challenge. Has anyone else made it out to their local observatories yet? This month there are IYA kickoff events happening all over the world, so now is a good time to check websites and see what is happening. I’ve discovered that there will even be local musical events in honour of the International Year of Astronomy, with music from the time of Galileo inside, and telescopes outside during intermission. Check your local astronomy club website for IYA events in your area.