On Monday, November 11, 2019, the planet Mercury lined up in such a way that it crossed the face of the sun from our vantage point on Earth. Because of the eccentricities and inclinations of the planets’ orbits, this is something that happens from time to time, like a lunar or solar eclipse. The last Mercury transit, as it is called happened in 2016, and the next will be in 2032. As it happened, this time our house was in a prime location to observe the event, and it was my day off. So I made some plans to have a look.
If you ever have opportunity to look at the sun, DON’T!! At least not if you don’t have the right equipment. Here’s a link to an article at Sky & Telescope with the right way to do it. If you follow the steps in the article, then it is a pretty cool thing to be able to do. Just be careful, or you or someone with you could go blind. You have been warned.
First viewing – Binoculars
Fortunately, I have the right equipment. I started out with my 10×50 binoculars equipped with solar filters that I had made for them before the 2017 solar eclipse. The sky was mostly clear but with patchy, high-level clouds, so not ideal, but a lot better than I expected. The transit started at about 7:30 a.m. EST, but I hadn’t convinced myself that I was going to be able to see anything yet, due to clouds, trees, and breakfast. I mean, it was my day off, and I don’t like getting up that early. By 8:15 I finally had enough coffee to begin executing my aforementioned plan. As you can probably tell, I’m not a really good planner, so when I say “I made plans to observe” what I mean is “I decided that I might give it a try and had a few options in mind about how to do so.” Any way, I went out in the front yard, which faces east and also a mess of trees, and found a spot on the front steps, actually, that had a clear line of sight to the sun. I got my binoculars fitted with their filters. Looking freehand was pretty much a No-Go. I had some hints that there was something there, but it was nothing I would swear to. So I got my camera tripod and attached the binocs, and that made all the difference.
I was surprised at how very small the planet Mercury appeared to be against the face of the sun. VERY small! Just a pinprick at about 8 o’clock and in from the edge maybe 1/6 to 1/4 the sun’s diameter. It’s no wonder I couldn’t make it out freehand. The streaky clouds often obscured it altogether. I tried taking some pictures with my phone, but that didn’t work well at all. The clouds were increasing, the sun was heading behind a tree, and I had seen the thing, so I felt pretty good, and went in, thinking I might be done. Then again, I might not.
Second Viewing – Reflector
The sky cleared a bit, and the day warmed a bit, so I decided to break out a telescope. I thought about trying to quickly build a filter for my 8″ Celestron Schmidt-Cassegrain telescope, and this is where being a real planner would have been useful, but there just wasn’t time on the spot to get a workable and safe solution. The other choices I had were that I have full aperture filters for my 60mm Meade ETX Maksutov-Cassegrain and my 5″ Orion SpaceProbe reflector. The 60mm is motorized for tracking, but it’s only slightly bigger than my binoculars. The 5″ is significantly larger but was at the time unmounted. I have two manual equatorial mounts that would work, one that came with the 5″ that is pretty wobbly, and one that came with my 8″ reflector that is more stable but sticky in its movement. I opted for the functional but wobbly 5″ reflector set up.
About 11:45 a.m. EST, I set up on the pool deck, which worked out well with an unobstructed view of the sun. Clouds were intermittent and didn’t hinder the viewing as much as they had through the binoculars. I was able to watch the second half of the transit. Using a phone adapter by Gosky or GoSky, I was able to take pictures and video of the event with my Samsung Galaxy J3. This was a mixed blessing as I have documentation of my observing and pictures and video I can share with you, but it’s a different experience viewing directly through the eyepiece as compared to viewing through the camera. I took turns between the two. I did enough direct visual to say I saw it, but I felt especially unsatisfied and satisfied for having video-recorded the 3rd and 4th contacts, that is the end of the transit, which was about 1:05 p.m. EST.
I used 20mm Super-Plössl, 10mm Plössl, and 8.8mm Wide Angle eyepieces with and without a 2x Barlow lens. This provided magnification of 45x, 90x, 102x, 180x, and 204x. Mostly I kept to the midrange 90-102x. The planet was much more obvious than in the binoculars and clearly a disk and not just a dot. Using the zoom on the phone camera means that I have no idea what magnification I actually had for any of the pictures. Because I changed the camera zoom many times, it has been very difficult to try to compare or stack the images, as they are at different magnification with different parallax error and different color balance. Because a Newtonian reflector gives a mirror image both left-right and top-bottom, Mercury appeared to be backing out the way I had seen it coming in through the binoculars, but it did in fact travel from SE to NW all the way.
I’m glad I got the chance to observe this transit directly. The last transit of Venus a couple years ago got completely clouded out. As I mentioned, the next Mercury transit will be in 2032. I wonder what sort of tech we will have to observe that event. I hope we’ll still be around to see it.
Here’s a link to my collection of photos for the event at Google Photos.