I'm trying to solve this task:

What is shown in the photo: a partial shadow eclipse of the Moon or a partial phase of a total eclipse of the Moon? enter image description here

I can't really understand it. Could somebody help please?


1 Answer 1


This is indeed a little confusing wording at first.

First, go compare this image to another image of the Moon (from Wikipedia or elsewhere) to find out which edge of the Moon is currently shadowed in the question, i.e north, south east or west edge. Since the Moon moves fairly close to the ecliptic, the Earth's shadow moves from west to east (from our perspective).

They could have rotated the moon arbitrarily to make the question harder; north might not be "up" in the image.

As a total lunar eclipse proceeds, the umbra first only partially covers the Moon; at first the west side, and at the end, the east site.

However, sometimes the Moon is slightly above or below the ecliptic, so it will be a partial eclipse. In that case the shadow still moves in the same direction, but it only crosses the north or south edge of the Moon.

Descending Node Lunar Eclipse Paths Source:

Descending Node Lunar Eclipse Paths

  • $\begingroup$ It seems to me that the image was not rotated and the shadow covers it's north part. So that means, in the image there is partial lunar eclipse. Is it right? $\endgroup$
    – ALiCe P.
    Aug 25, 2021 at 7:42
  • $\begingroup$ @Alice in this case I think I should recommend how to solve the task, but not actually solve it for you. But I can say that your reasoning seems sound :-) $\endgroup$
    – uhoh
    Aug 25, 2021 at 9:27

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