Best Solar Images - Part 4

Special Events

My solar imaging activities are coming to an end. I've spent 15 years happily watching the ever-changing solar chromosphere and capturing images with my solar telescope. Now is a good time to look back at some highlights and gather my best images together in one place. In this fourth post I'll present images of unique solar events and activity I was fortunate enough to observe. In an upcoming post I'll present my best sunspot images.

All images presented here were made with a Lunt 100mm single-stacked hydrogen-alpha solar telescope. Each image will indicate the camera and Barlow lens used. Often, single image fields of view were combined to include larger portions of the Sun. These separate panels were later stitched together into a single combined image using Photoshop.

The Sun's color seen by eye through the Lunt telescope's eyepiece is not yellow but rather a deep hydrogen-alpha red. The cameras I used are monochromatic cameras which produce only black and white images. I have arbitrarily added different colors to the original grayscale images below. These added colors have no physical significance. I merely liked them better than grayscale.

Finally, these images are best viewed at full size on a monitor, laptop screen, or projected on a TV. Smart phone viewing is a disappointing experience. Click on the images to get the full-size version.

Sometimes, just by pure luck, I happened to be observing when solar activity increased. For example, on October 17, 2014, I saw sunspot 2192 emit a rapid spike off the limb from a white area near the umbra. Sunspot 2192 was just emerging around the eastern solar limb. The next image made with a DMK41AUO2.AS camera and 2X Barlow lens shows the spike. The image is processed to enhance relatively dim features, so the disc is overexposed.

When I saw rapid changes near this sunspot, I began capturing one image every 60 seconds for 66 minutes from 2:37 EDT to 3:43 EDT. The images were then assembled into the following time lapse movie where 66 minutes of action are compressed into 6.6 seconds. The movie shows the dramatic spike eruption as well as changes in the neighboring prominence. The 35MB movie might take a while to load, but it's worth the wait!

Sunspot 2192 was quite a performer! Eight days later on October 25, 2014, at 1:57 EDT I captured the following image of 2192 which had now rotated past center on the solar disc. The white overexposed area in the next picture is a powerful solar flare! (All October 25, 2014, images were made with a DMK41AUO2.AS camera with a 2X Barlow lens.)

At 3:09 EDT after 69 minutes elapsed the flare had diminished as seen in the less dramatic overexposed area in the next image.
The flare had actually peaked at 1:09 EDT according to space weather websites. So, my first observation was 48 minutes after the officially reported peak. The flare was diminishing when I observed it. If I had begun observing an hour sooner, I would have captured the rise of the flare toward its peak instead of its decline.

The following 22-panel mosaic shows the sunspot 2192 flare as it appeared in context on the entire solar disc.

This was an X1 flare, the most powerful class of solar flares. Solar flares are classified according to their rate of energy output in X-rays. An X1 flare gushes energy at a rate greater than 0.0001 watts per square meter in X-ray wavelengths between 0.1 and 0.8 nanometers as measured by detectors in geosynchronous orbit around Earth. This 0.0001 watts may not seem like a lot of power per square meter, but this is the flux measured near Earth far away from the concentrated source on the Sun. By the time X-rays travel to Earth from the Sun they have spread out over a tremendous area. A square meter near Earth receives only 0.0001 watts, but at the source on the Sun energy is emitted at the rate of about 14 billion gigawatts!!! That's equivalent to the power output of 14 billion nuclear power plants!! It's a good thing we're so far from the Sun!

After collecting images for the disc mosaic above I thought the active sunspot might still be changing enough to make an interesting movie. So, I recorded movie frames, one every 60 seconds, beginning at 3:08 EDT. When 30 minutes had elapsed, it seemed like nothing was happening, so I stopped recording at 3:38 EDT. The 31-frame movie below shows the aftermath of the flare. At the beginning of the movie white areas are brightest. Over the next 30 minutes brightness diminishes as the flare continues to die down. The spot was perfectly positioned for making a long movie. Unfortunately, I gave up too soon! Lots of details are changing within the sunspot group, although these changes weren't easily apparent as I captured video clips one by one. The October 25, 2014 flare was the biggest one I ever saw during 15 years of observing.

Using a DMK41AUO2.AS camera and 2X Barlow lens on March 29, 2015, I captured a different eruption on the limb in a single image shown next. The eruption changed relatively rapidly, but I didn't attempt to make a time-lapse movie this time. 

On September 14, 2015, another spike eruption happened near sunspot 2418. The following single image was made with a ZWO ASI174 camera and a 5X Barlow lens. 

Continuing with unusual events, I was lucky enough to capture a transit of Mercury on May 9, 2016! Mercury lines up in front of the Sun every 115.9 days as seen from Earth. During these alignments Mercury is usually above or below the Sun, but, sometimes, Mercury transits directly across the face of the Sun as it did on May 9th. There are 13 or 14 Mercury transits per century compared to only two for Venus. I've been fortunate to see both Venus transits in 2004 and 2012, but I'm running out of time for transit observing. Another Mercury transit happened in 2019, but I missed that one. At this point there will be no Venus transits for the remainder of my life. I will be taking a dirt nap before the next Mercury transit occurs in 2032! So, I was motivated to make extra effort to observe the 2016 transit in spite of cloudy conditions. The next image made with a ZWO ASI174MM camera and 5X Barlow lens shows Mercury's black disc against the background Sun. The angular diameter of Mercury's disc here is only 12 arc seconds. 
Another unusual event was the partial solar eclipse of August 21, 2017, visible from my backyard in Williamsburg, VA. Using a ZWO ASI174 camera with a 5X Barlow lens I recorded the passage of the lunar disc across various parts of the Sun. Watching the Moon approach and cover elongated sunspot 2671 was particularly nice! The first picture below is a single image of 2671 with the curved lunar limb approaching to its right. I made two time lapse animations - one as the lunar limb approached and one as the lunar limb receded from 2671. 

Finally, I observed a minor flare in sunspots 3116 and 3112 on October 7, 2022, with a ZWO ASI174MM and 3X Barlow. The next picture is a single image of the sunspots with the white overexposed flare to the left. 

I made an animation covering 21 minutes of the October 7, 2022 flare activity. 

My next post will feature sunspots.