Contains:  Solar system body or event
Eclipsed Moon and Umbral Shadow, Alan Dyer
Eclipsed Moon and Umbral Shadow, Alan Dyer

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Description

The Moon in total eclipse, on January 20, 2019, in a multiple exposure composite showing the Moon moving from right to left (west to east) through the Earth’s umbral shadow.

The middle image is from just after mid-totality at about 10:21 pm MST, while the partial eclipse shadow ingress image set is from 9:15 pm and the partial eclipse shadow egress image set is from 11:15 pm.

I added in two images at either end taken at the very start and end of the umbral eclipse to add a more complete sequence of the lunar motion. However, on those images the lunar disk is darkened mostly by the penumbra.

All images are with the Canon 6D MkII on a Fornax Lightrack II tracking mount to follow the stars at the sidereal rate, to keep the stars fixed and let the Moon drift from right to left against the background stars.

Thus, the Moon images are where they were in relation to the background stars and therefore show the Moon’s motion through the umbral shadow, with the shadow edge on the partially eclipsed Moons defining the shape of the large and circular umbral shadow of the Earth, approximately three times bigger than the Moon. At this eclipse the Moon moved across the north edge of the umbral so we are seeing the top of the shadow circle drawn here in the sky.

At this eclipse the Moon was also shining beside the Beehive star cluster, Messier 44, in Cancer. This was the unique sight at this eclipse as it can happen only during total lunar eclipses that occur in late January. There was one on January 31, 2018 but the next will not be until 2037.

The central image of totality includes a 1-minute exposure at ISO 800 and f/2.8 for the stars, which inevitably overexposes the Moon. So I’ve blended in three shorter exposures for the Moon, taken immediately after the long “star” exposure. These were 8, 4 and 2 seconds at ISO 400 and f/4, and all with the Canon 200mm telephoto.

The two partial eclipse phases are stacks of 7 exposures each, from very short for the bright portion of the lunar disk, to long for the shadowed portion. They are blended with luminosity masks created with ADP Pro v3 panel for Photoshop, but modified with feathering to blend the images smoothly. This sort of “HDR” blending is necessary to depict the eclipsed Moon as your eye saw it, as while the eye can encompass the great range of brightness across the eclipsed Moon’s disk the camera cannot. Even the totality image is a blend of exposures, as the top part of the Moon was quite bright at this eclipse due to the Moon’s path across the northern half of the umbra.

The timing of the partial eclipse images about 1 hour before and 1 hour after the central image places the lunar disk against the stars so those disks don’t overlap. But ….

….The images aren’t quite symmetrical for shadow placement and phase, because as luck would have it, the drive of the Fornax tracker, which has a limited travel, decided to run out of travel right at mid-eclipse at 10:15. All is needed was another 10 minutes of travel, but no!

This required resetting the drive, then reaiming and reframing the camera right at the worst time, and taking time. So the timing and orientation of the latter images were compromised, requiring a little fudging on my part to place the egress set. However, the overall placement of the Moon and shadow is close to reality and the composite serves to illustrate the concept.

These were taken from a site near Lloydminster, in Saskatchewan, where skies proved clear all night, better than the prospects back at home 500 km farther south in Alberta. It was worth the drive north the day before the eclipse.

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Eclipsed Moon and Umbral Shadow, Alan Dyer