Objects in Transit

This year has been remarkable in that we’ve have two major solar transit events close together. The first was the annular eclipse of the sun by the moon on May 20, 2012. The other was the transit of Venus across the face of the sun just two weeks later on June 5, 2012. I was lucky enough to be at Kitt Peak National Observatory for both events. Despite the fact that I operate the two largest telescopes on the mountain—the 4-meter and the WIYN 3.5-meter—most of my viewing was simply by eye with “solar viewing glasses” I picked up from the Kitt Peak visitor center or through my Kodak camera, using the same glasses. The reason for this is that those large telescopes are simply not designed to handle sunlight. They would be seriously damaged looking at the sun just like your eye would be without help.

This first photo shows the annular eclipse near Maximum at Kitt Peak. It’s taken with my digital camera through the solar viewing glasses. Kitt Peak was a little too far south to see the full annular eclipse, but the moon still did cover much of the sun. Note, clicking on the images will bring up larger views.

Here’s a photo I took of the transit of Venus using the same camera. What amazed me was that using this ordinary digital camera, not only could I see Venus (the dark spot on the right), but I could see sunspots (the lighter spots to the left).

I was especially gratified to see the sunspots since a lot of my early research in astronomy was geared to something called RS Canum Venatacorum stars. These are binary stars about the size of the sun, but with observable star spots.

Being at Kitt Peak, I was able to see the sun through small amateur telescopes with solar filters. That allowed me to see a little more detail than I could just by eye or through the camera. Here’s a little better view of transiting Venus along with a clearer view of the sunspots.

One of the other telescopes that I was able to look through included a Hydrogen-alpha filter that blocked out a lot of the sun’s glare. The photo I took has a lot of ghosting in the center, but you can still see solar prominences—flame like structures— around the outer edge of the sun at about 2 o’clock and 5 o’clock. Keep in mind, those prominences are bigger than the Earth!

What really amazes me about seeing the transit of Venus is to realize that this is the same technique we’re using to discover many of the other planets around other stars. Basically we’re looking for that little bit of star light blocked out when a planet goes between us and that star. Many of those planets do this a lot. There are planets with years as short as 2 or 3 days!

Astronomer and science fiction writer Mike Brotherton pointed out something to me that’s fun to ponder. While we were watching the transit of Venus, it’s always possible that some extraterrestrial civilization was observing both Earth and Venus transit the sun and realizing there are planets here.

Just remember, if you want to go out and view the sun, make sure you do so using sufficient eye protection such as these solar viewing glasses, available from Amazon.