Solar Eclipse!

A Special Day

The solar eclipse on August 21st was only partial at my home in Williamsburg. From my back yard, at maximum eclipse, 88 percent of the solar diameter was blocked, and 85.6 percent of the solar area was covered. Years and months before the eclipse I debated the merits of traveling somewhere to be in the path of totality. If I traveled, I wouldn't take my solar telescope. I would experience totality, but probably not get any worthwhile images. If I stayed home, I could try using my telescope to get hydrogen-alpha images of the lunar limb covering solar features. In the end, I decided to stay home and see how my telescopic imaging system would perform.

Several weather forecasts predicted nearly clear skies for August 21st. I set up my equipment hours before noon to be well prepared for the afternoon eclipse. I also wanted to get images of sunspots on the solar disc before the Moon came on the scene. Fortunately, a major sunspot group was located near center on the solar disc along with another smaller group near the western limb. These provided nice background features for the Moon's limb to cover during the eclipse. The Sun had often been nearly featureless recently, so the appearance of these sunspots was an unexpected bonus.

As often happens, predictions of cloud coverage were inaccurate. Near 10:00 am EDT several drifting clouds were present, but not enough to make imaging impossible. At 10:14 I captured the following image of large sunspot group 2671 near center on the solar disc. Lots of complex structure is visible. (Click on any image below for larger views.)

Clouds soon increased. It became harder to find clear gaps large enough to get an unobstructed view. I had to wait 35 minutes before getting one chance to capture the other sunspot, 2672, seen below.

At this point things looked bleak for viewing the afternoon eclipse! I shut down my equipment and had some breakfast.

Two hours later my telescope and computer were powered up and ready to go for the beginning of the eclipse. Clouds with gaps drifted across the sky. The Sun crossed the meridian at 1:10, so I waited until then before locking the telescope on the Sun. (This avoided an inconvenient meridian flip required by my German equatorial mount.) The first appearance of the Moon's black disc on the Sun's edge was scheduled at 1:20. I wasn't quick enough to capture this event. My first image at 1:26 was unremarkable, but 18 minutes later, at 1:44, the Moon's edge appeared just to the right of (west of) the largest umbra in sunspot group 2671 as shown below.

Seven minutes later the lunar limb (moving right to left, or, eastward) had passed the large umbra and moved over erupting white energetic emissions shown in  the next picture.

By comparing the two previous images you can see how much the Moon had moved in about 7 minutes. The Moon's eastward motion relative to the Sun was easily visible in real time on my laptop screen as smaller solar features were continuously eclipsed. This was a rare opportunity to witness lunar orbital motion with only a few seconds of observation!

I wondered if lunar motion would smear out detail along the lunar limb. This turned out to be true. Most of my video clips were limited to 400 frames which took about 11 seconds to record. The image processing software I use to produce still images from the video clips did a good job with relatively steady solar features, but detail along the lunar limb was not resolved. The software produced a thin bright border along the moving lunar limb.

I thought an image of the lunar limb crossing a sunspot umbra would be interesting. Unfortunately, a big cloud blocked the Sun at the moment this crossing occurred. So I have only before and after crossing pictures above. By the time clouds thinned somewhat, the entire sunspot group had been covered, and the lunar limb was moving over bland surface features.

Two modest prominences were present on eclipse day. Another interesting image, I thought, would be the lunar edge crossing a prominence on the Sun's limb. The next image shows one such event where you can see the Moon's limb extending beyond the solar disc.

My daughter's family, one of her friends, and some of our neighbors also viewed the eclipse with me. I was so happy to share my astronomical enthusiasm for a couple hours. In the next image my daughter is looking through eclipse glasses while I'm watching a magnified telescopic hydrogen-alpha view on a laptop screen. The laptop is shaded by a cardboard box, and I'm shaded by an effective clamp-on umbrella recently purchased.

My little granddaughter, Annabelle, was happy to play for a while on her blanket. You can see the partly clouded sky in the background.

My other granddaughter, Sophie, pronounced eclipse views, "Cool!". She shared a view of my laptop screen and also saw the entire solar disc in hydrogen-alpha through my telescope. Not many 7-year-olds can claim the same experience.

Of course, we had to try the old "colander" trick showing multiple crescent images of the nearly maximum eclipsed Sun. I had never noticed the appropriate star-shaped hole pattern before.

We had two pairs of solar filtered binoculars, eclipse glasses, the telescope, and various pinhole devices. My son-in-law had fun looking through all the various optical instruments.

Sophie and her close friend, Portia, shared a view through filtered 100X25 binoculars.

Eclipse maximum happened at about 2:46. The sky became noticeably dimmer for a short while near this time. Soon after maximum clouds began to thin and seeing became much better as the atmosphere steadied. At 3:00 I captured the following view of the largest solar prominence being uncovered by the receding Moon. (The Moon is moving from right to left here.)

Ten minutes later I could see large sunspot group 2671 being uncovered as the Moon continued moving eastward across the Sun.

Fourteen minutes later all of sunspot group 2671 was uncovered.

Just before 4:00 sunspot 2672 was completely uncovered.

The Moon's "bite" on the Sun was rapidly diminishing. At 4:04:40, just 39 seconds before the predicted end of eclipse at my location, I captured this final view of the lunar limb leaving the Sun.

After the eclipse I felt exhilarated, but also completely exhausted. Heat drains my energy. The temperature had been in the low 90's since noon. My shirt was soaked through, especially after hauling all the equipment inside. I could barely keep my eyes open for the rest of the day, including during a dinner to celebrate C's birthday, which, coincidentally, also fell on eclipse day!

I might be able to use some of the many images not included here to create an animation showing the Moon covering the large sunspot group. Perhaps I'll include that in my next post.