Elusive Mercury Makes an Appearance

I was the first to arrive to set up at Floyd Bennett Field in Brooklyn just before 7:00 a.m. for the Transit of Mercury. A handful of hardy souls then began to pull in to join me in the early morning to catch first contact of the transit at 7:35 a.m. The intrepid early observers included AAA site chair Arthur Kunhardt; past AAA and current ASLI member Steve Lieber, and AAA member Thomas Evangelis. Also joining us in the early morning were a parent and two of Tom’s students from Brooklyn Tech. Although it was a little chilly with some light wispy clouds, it was a bright, beautiful morning and it appeared that we would have a good chance of witnessing the transit. Also, thankfully, Steve and the dad each brought hot coffee for all.

For my gear, I brought the 3-1/2-in. f/15 “Thompson” Brashear refractor (alt-az with drive handles) and a Brashear Herschel wedge — a sophisticated solar filter system that works at the eye end rather than covering the aperture. A modern Televue Nagler 13mm eyepiece gave 103X, the right magnification to see a good disk of the planet’s silhouette without the unsteady air interfering. I was the only one who was at the eyepiece when it was predicted for first and second contacts. First contact is tough to catch because you don’t know precisely where it will appear and the sun’s edge is tremulous in the low sky. However, I caught it right at the start. On the east (trailing) side of the sun, it started to stand out slightly at first and then it became a dark “scallop.” Not long after, it was a fine spectacle to see half of Mercury’s disk in silhouette, then the full disk, and finally separation from the limb. A few minutes after, I took two images with my phone camera, with some light clouds apparent.

Tom brought a Celestron C-8 with a white light filter. This performed very well. He also brought a 60mm Coronado solar telescope which was not performing well, and it went back in the case. Steve Lieber used a Televue Pronto with a Coronado and two etalons (double stacked). For the first few hours, he viewed at 48X, then at 40X.

Steve said that “the double stacked arrangement showed granulation on the Sun, but little else. Then I took off one of the etalons. This was not only brighter, but it also allowed me to tune the filter and view a small prominence in the northeast. It was fascinating to watch how it would change shape in only a few minutes’ time. A second, smaller one appeared a little more east of that time. This also changed quickly. Keep in mind the size of the prominences. The material must be moving incredibly fast.”

I was lucky when I snapped some shots with my phone camera. Heh, even a blind squirrel finds an acorn sometimes! While the few images that I captured are surprisingly good, the visual imagery at the eyepiece was actually much sharper and the inky blackness of the planet’s silhouette was a sight to behold. This is typically the case, especially with planetary viewing. According to Steve, the clouds stayed thin until about 10:30 a.m. Around 12:00 p.m. the clouds were too heavy to observe, but that was short-lived. Generally, the group was able to observe almost continuously from start to finish. During the entire event, about 30 people showed up, with most staying for only part of the transit. Steve also mentioned that “Two reporters from Space.com showed up. They interviewed a few of us.… Another attendee was Martin Evans who had been a reporter for Newsday….”

Although the transit was 5-1/2 hours long, I stayed only until 9:30 a.m. and drove back home. But since it was still sunny enough, I put the telescope back up in our rear yard. Our son Ian and I continued to watch the progress, intermittently, as Mercury completed its travels across the face of old Sol. Since I saw the ingress at Floyd Bennett Field, Ian had the privilege of watching third and fourth contacts, or egress. I casually timed it as he called out when Mercury touched the sun’s limb and then again when it finally disappeared off the unsteady edge of the sun’s disk. It took approximately one minute for that to occur. That was from 1:04 to 1:05 p.m. Five minutes later, the telescope was back in our living room, looking elegant, the end of a very memorable astronomical event. Little Mercury is elusive being so near the sun. Kind of him to make this appearance!