Mercury Transit in SJ

by Mark Brada

Mercury Transit, 8 November 2006

The weatherman had forecast light rain on Wednesday morning, but as I had promised my students a chance to see the transit, I went ahead and packed up my gear on Tuesday evening for the ride to school the next morning. I guess I was just feeling hopeful after the election results on Tuesday night. The mount and solar scope easily fit in the hatchback with plenty of room to spare. I went to bed thinking that the weather forecast might be some kind of delayed karmic retribution for purchase of the scope two months earlier. I turned to my statue of Quan Yin (OK…it’s really a lamp) in the hopes of being granted some mercy for my transgression.

It would have been great to join up with everyone that was going to Houge Park, but the whole job thing sort of got in my way. I was determined to at least show some of my students the transit, however. On my drive to work this morning, though, I was not hopeful. The entire South Bay seemed hopelessly socked in by clouds that threatened rain or at the very least utter bleakness for the entire day. I dragged myself into my classroom and got to work catching up on some grading and preparing for my lectures for the day. I was engrossed by my work until around 10:45, when I looked out the window of my classroom. It still looked bad from where I sat, and I was about to give up on the idea of setting up at all. After a quick chat with a colleague, though, I glanced out the southern facing window one more time. What’s this?! Blue skies at last! The clouds broke literally at the last moment. It was surely a sign, and I couldn’t pass up the chance. I quickly grabbed the equipment out of the car and ran over to the field to set up. I was not disappointed.

I had missed the ingress by about 15 minutes or so; by the time I got a good image at the eyepiece, Mercury was already well along its merry way across the disk of the sun. I had roughly 20 to 25 students drop by to have a look, and there were many “Ooohs!” and “Ohs!” and “Wows!” I couldn’t have been more pleased. I was set up for just over an hour at lunch, and it was almost magical to watch to progression of the tiny speck of Mercury as it marched along its merry way across the solar disk. One of the most awe inspiring aspects of the transit, at least to me, was the sheer size of Sol compared to the tiny Mercury. There was an impressive sun spot near the limb of the sun that stayed there more or less all day which was immensely larger than Mercury (at least five times Mercury’s diameter), in spite of the messenger planet being 36 million miles closer to us than the sun. Indeed, there were many prominences that were much larger than Mercury as well. I was using relatively low power (27X and 33X) to frame the entire solar disk in the field of view. Although there was some light wind, the seeing seems quite stable to me. The outline of Mercury's disk was rock steady for the entire time I was out during lunch.

Alas, the fun was over for me at about 12:40, though, as I had a class that started in 10 minutes. I quickly packed up (I can carry the entire set up in one trip, but it’s slightly challenging to do so) and dropped everything in my room just in time to greet my afternoon students.

After teaching for a few hours in the afternoon, I was about to slog off to a budget meeting for next year when my department chair approached me and asked if I wouldn’t mind missing the meeting to set up my telescope so the other members of the department could get a look see at the transit. Mind? I was ecstatic, of course. I quickly grabbed everything out of my room and ran out to find a spot to set up in. The sun was fairly low in the west by now (around 3:20pm or so), but I found a spot that was not yet obstructed by a building or a tree. This time around I had a continuous stream of people, about half of them colleagues and the other half students, lined up at the scope to see the transit. It was very gratifying for me to have so many students show so much interest. At one point, one of my colleagues asked me if part of the disk was suppsed to be cut off. I was thinking the sun must have drifted out of the field of view, but when I looked through the eyepiece, I realized it was dropping behind the building! I quickly picked everything up and retreated to higher ground. The line petered out at about 4:08, and I was lucky enough to be able to watch the entire egress. Near the end of the egress, the seeing was getting pretty spotty, and it was a bit hard for me make out the small bite out of the sun at the very end of the egress. Almost immediately after the egress ended, the sun began to drop below the building I was looking over and I had no more room to move, so I packed it all in at around 4:15.

All in all it was a most satisfying event for myself, and an exciting day for 40+ members of my high school community.

Posted on sf-bay-tac Nov 08, 2006 21:05:17 PT
Converted by report.pm 1.4 Dec 12, 2006 21:54:03 PT