But do you know what it is? Take a look at this great picture of gegenschein, taken by Yuri Beletsky at the Very Large Telescope in Chile. On dark nights, in places well away from light pollution, you might be able to see this faint band of light that is NOT the Milky Way Galaxy but is, instead, the light of the Sun being reflected off of interplanetary dust particles in our solar system. It lies in the ecliptic, which is the plane of our solar system. So, when you see the gegenschein you’re seeing another part of the solar system — diffuse dust. It’s everywhere!
A couple of entries ago I talked about observing on Mauna Kea in 1996. I suppose I went into it with only a little bit of a romantic view of Big Astronomy Observing, knowing that it wouldn’t quite be like the days of old with the lonely astronomer sitting in the cage while the selfless night assistant monitored the proceedings and moved the telescope at my command. For one thing, I knew that modern observatories use computers to position their telescopes precisely, and that most observers sit in nice, comfy control rooms and not in drafty chairs on the telescope, peering through eyepieces.
Our own observations on Mauna Kea made heavy use of computers to quickly capture images and do some quick processing to make sure we got what we wanted, before moving on to the next target. Our observing runs were chock full of targets: Comet Hale-Bopp, Comet Machholz, an assortment of asteroids, and just for grins toward the end of the night, we targeted a few deep-sky objects before we shut the systems down. If we’d had to go out on the observatory floor and manually position the scope for all those objects? Well, it wouldn’t have happened.
Control room at the UH 2.2-meter telescope in 1996
Computers revolutionized astronomy and nowadays you see amateurs routinely hooking up their Dells and IBMs and other systems up to guide their telescopes. Many amateur scopes have their own onboard guiding systems, complete with star ephemeris information and more. Heck, you see them being run from laptops and Personal Digital Assistants! It’s a far cry from the early days when the computers at observatories were pretty much limited to guiding the telescope for precision pointing. Today they also monitor the instruments attached to the telescopes, record data, and in some cases do what is called “pipeline” processing to get it ready for the observer who got the telescope time in the first place. It’s safe to say that most of modern astronomy would be impossible to do without computers.
There are those who bemoan the loss of the “old days” when the observer had complete control of the process, sort of like a king on a throne, but I think those folks are few and far between. Far from computerization being a tool to remove power from lofty astronomers, it has democratized the process for more observers and made a great deal more science possible. Without it, the wonderful images from the Hubble Space Telescope, Gemini Observatories, Spitzer Space Telescope, the myriad amateur astronomers who turn out breathtaking work, and so many others would not exist.
