Lunar Eclipse Through the Clouds

I have been looking forward to the recent Lunar eclipse (20 January 2019) since, well, the last one actually. During that eclipse, I shot images every three minutes while using an equatorial mount to track along with the stars. The results were good but there was some room for improvement. And that’s why I was looking forward to this event.

Lunar eclipse of 20 January 2019.
Lunar eclipse of 20 January 2019.

The weather had different plans for me. A stream of high-level tropical moisture was sitting right over Arizona all that day and most of the night. By late afternoon, the clouds were thick enough to partially obscure the sun. How was a darkened Moon going to shine through those clouds?

I could have just given up and stayed home but I was determined to at least try. I drove to Sedona to set up. Not because Sedona is a better place for viewing than Flagstaff but because Sedona is about 15 degrees warmer. And that matters.

I set up the tripod and then roughly aligned the iOptron Skytracker to where I made my best guess of the location of the star Polaris. Just as the umbral phase of the eclipse began, I was able to barely see Polaris through the thin clouds and completed the alignment of the tracker.

One of the things I learned last year was that three minutes was too large a time gap to make a smooth time-lapse video. My plan for this eclipse was to shoot at 1-minute intervals. But with the high clouds I realized that any time-lapse video was going to be challenging. So…3-minute intervals again. The clouds varied between fairly thick and mostly obscuring the moon to occasionally very thin allowing some lunar detail to be seen.

Satellite image showing extensive clouds during the Lunar eclipse.
Satellite image showing extensive clouds during the Lunar eclipse.

Here is a satellite image from GOES-16 showing the incredible stream of clouds moving across Arizona. I’m amazed that I got any photos at all!

An Early Morning Lunar Eclipse

It was worth it.

Getting up early in the morning, driving to a location with a good western view, and then standing around for many hours taking photos of the lunar eclipse.

Yes, it was worth it. But I was very cold by the time it was over.

Four stages of the total lunar eclipse of 31 January 2018.
Four stages of the total lunar eclipse of 31 January 2018.

This lunar eclipse has been referred to as the “Super Blue Blood Moon” eclipse. What does that even mean? Okay—here is an informative article written by an astronomer on how these terms came to be part of our jargon for this eclipse.

Anyway…

I had considered many possibilities how to photograph the lunar eclipse including interesting foregrounds, multiple exposures, and even video. Some examples of single and multiple images can be found in this blog for 2014 and 2015 eclipses taken during the recent Lunar Eclipse Tetrad of 2014-2015. A tetrad is a series of four consecutive total eclipses occurring at approximately six month intervals. It’s now been a bit more than two years since the last lunar eclipse visible around here and I was ready for another.

Start of totality.
Start of totality.

Eventually I decided to try something a bit different from previous events. I would mount the camera on the iOptron SkyTracker so that the camera would follow the stars. From these images, I would construct a time-lapse of the eclipse as it went through its different phases. With the SkyTracker, the stars would remain fixed while the moon would slowly move across the sky relative to the stars—and the Earth’s shadow.

Mid-totality of Lunar Eclipse.
Mid-totality of Lunar Eclipse.

It worked pretty well but I did manage to bump the camera a few times as I was changing exposure settings. I had considered using a phone application that could change the settings on the camera so I would not have to touch it—but the power drain when WiFi was active was unacceptable. I would probably need to change the battery during the eclipse—which put me right back in the same situation of jostling the camera. Okay—just keep it simple. No WiFi, adjust by hand, and be careful.

The image at the top of this entry is a composite of four stages of the eclipse. P1 is the first stage when the Moon enters the Penumbral shadow of the Earth. Only a subtle darkening occurs during this stage. U1 occurs when the Moon first enters the umbral shadow and the darkening along one edge is very distinct. U2 is the beginning of totality. Mid-totality is the darkest stage of the eclipse.

The second image shows the start of totality. There is a brief period near the start and end of totality in which the limb of the moon can have a bluish cast to it.  Lunar eclipse researcher Rich Keen says:

“Most of the light illuminating the Moon passes through the stratosphere, and is reddened by scattering. However, light passing through the upper stratosphere penetrates the ozone layer, which absorbs red light and actually makes the passing light ray bluer.”

This can be seen as a turquoise-blue fringe around the red. And here we have an image taken just a few minutes after totality began that shows some blue along the lower limb.

A few minutes after totality ended—and a few minutes before moonset.
A few minutes after totality ended—and a few minutes before moonset.

Stages P1, U1, U2, and mid-totality were all visible with a very dark sky. U3 (end of totality) occurred during morning twilight; U4 and P2 both occurred after Moonset.

The time-lapse sequence was shot with 3-minute intervals. This is a good interval if you want to composite images as the moon has moved a full diameter plus a bit more in three minutes so that individual frames do not overlap. Three minutes, however, is too long a time for a smooth time lapse. Lesson learned for the next event!

The animation of the eclipse starts at P1 and ends just as the moon sets. The exposure was changed during totality and stars become visible. Later, twilight brightens the entire sky and, at the end, the distant mountains can be seen as the moon sets in the west.

 

The next total Lunar Eclipse will occur 27 July 2018 but will not be visible from any part of North America. The next North American total lunar eclipse will occur on 21 January 2019.

Edit: corrected dates.