APOD: The Moon During a Total Lunar Eclipse (2021 May 25)

[APOD Robot]

The Moon During a Total Lunar Eclipse

Explanation: How does the Moon's appearance change during a total lunar eclipse? The featured time-lapse video was digitally processed to keep the Moon bright and centered during the 5-hour eclipse of 2018 January 31. At first the full moon is visible because only a full moon can undergo a lunar eclipse. Stars move by in the background because the Moon orbits the Earth during the eclipse. The circular shadow of the Earth is then seen moving across the Moon. The light blue hue of the shadow's edge is related to why Earth's sky is blue, while the deep red hue of the shadow's center is related to why the Sun appears red when near the horizon. Tomorrow, people living from southeast Asia, across the Pacific, to the southwest Americas may get to see a Blood Supermoon Total Lunar Eclipse. Here the term blood refers to the (likely) red color of the fully eclipsed Moon, while the term supermoon indicates the Moon's slightly high angular size -- due to being relatively close to the Earth in its slightly elliptical orbit.

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[heehaw]

Mooning us!

[Ann]

Mooning us!

Almost looks like it's got two cheeks, one gray, one red.

Where's the "giggling and blushing" emoji?

Ann

[dddavids]

Why does the edge of earth's shadow appear to move across the moon's face from 7 o'clock to 1 o'clock beginning the eclipse, but from 5 o'clock to 11 o'clock ending the eclipse?

[orin stepanek]

So many colors; which one to choose!

The blood Moon (Luna) depicted for tomorrow?

[Chris Peterson]

Why does the edge of earth's shadow appear to move across the moon's face from 7 o'clock to 1 o'clock beginning the eclipse, but from 5 o'clock to 11 o'clock ending the eclipse?

Keep in mind that the Moon rotates with respect to the horizon as it crosses the sky- nominally by 180° from one horizon to the other. In this video, the individual frames have been rotated to keep the orientation of the Moon fixed, which means the sky itself, including the direction Earth's shadow is moving, must be rotating. As the eclipse sequence is several hours long, the amount of rotation is significant.

[DL MARTIN]

Whatever you say Chris and I mean that as a compliment.

[Chris Peterson]

Whatever you say Chris and I mean that as a compliment.

Another factor to consider is that unless the Moon passes directly through the center of the Earth's shadow, the leading and trailing edges will be at different angles. I didn't look up the details of the eclipse in this video, but that's a big factor in tomorrow's eclipse, which is almost grazing.

[orienteer6]

What does the earth look like from the moon during our lunar eclipse? I am imagining a black circle with a red ring of atmosphere. Is the sun show the corona like our solar eclipse? Is the sun large enough that it can still be seen?

[neufer]

Almost Grazing

Almost Grazing.png (22.64 KiB) Viewed 3200 times

Another factor to consider is that unless the Moon passes directly through the center of the Earth's shadow, the leading and trailing edges will be at different angles.

I didn't look up the details of the eclipse in this video, but that's a big factor in tomorrow's eclipse, which is almost grazing.

[Chris Peterson]

What does the earth look like from the moon during our lunar eclipse? I am imagining a black circle with a red ring of atmosphere. Is the sun show the corona like our solar eclipse? Is the sun large enough that it can still be seen?

Yes, a black disk with a thin glowing band around it, that will vary from nearly white to quite red, and vary at different point as well, depending on the global atmospheric conditions. You might also see blue at the outside of this ring from atmospheric ozone.

This disk will subtend about 2°. While the solar corona extends quite a bit more than this, the inner corona, bright enough to be visible to the naked eye, does not. But during parts of the eclipse, when the Sun is blocked but is close to the edge, it seems likely that parts of its corona might be visible.

Such an eclipse (lunar from Earth, solar from the Moon) was captured in 2009 from the Japanese lunar probe Kaguya.
_

Click to play embedded YouTube video.

[De58te]

What does the earth look like from the moon during our lunar eclipse? I am imagining a black circle with a red ring of atmosphere. Is the sun show the corona like our solar eclipse? Is the sun large enough that it can still be seen?

This is my layman views, but since the eclipse is mainly over the middle of the Pacific Ocean at midnight the Earth will be mostly black with the bright city light of Los Angeles and San Fransisco at one side and the lights of Sydney Australia on the other side.

Since the Earth is some 4 times bigger than the Moon, just over 2,000 miles diameter for the Moon and 8,000 miles for the Earth, and the distance between the two is the same, then more of the Sun's corona would be blocked by the Earth. Maybe the outer parts might be visible but I don't really know how large the corona is.

If the Sun can be blocked out by the Moon at a solar eclipse then the 4 times larger Earth would block out the Sun. Of course there is the bending of the light through the atmosphere that refracts the red light.

[orienteer6]

Yes, a black disk with a thin glowing band around it, that will vary from nearly white to quite red, and vary at different point as well, depending on the global atmospheric conditions. You might also see blue at the outside of this ring from atmospheric ozone.

This disk will subtend about 2°. While the solar corona extends quite a bit more than this, the inner corona, bright enough to be visible to the naked eye, does not. But during parts of the eclipse, when the Sun blocked but is close to the edge, it seems likely that parts of its corona might be visible.

Such an eclipse (lunar from Earth, solar from the Moon) was captured in 2009 from the Japanese lunar probe Kaguya.

Thanks Chris, great video

[orienteer6]

thanks to DE also, I did not see your post until I posted my thanks.

[NateWhilk]

Why does the edge of earth's shadow appear to move across the moon's face from 7 o'clock to 1 o'clock beginning the eclipse, but from 5 o'clock to 11 o'clock ending the eclipse?

Another factor to consider is that unless the Moon passes directly through the center of the Earth's shadow, the leading and trailing edges will be at different angles. I didn't look up the details of the eclipse in this video, but that's a big factor in tomorrow's eclipse, which is almost grazing.

Here's a clip showing how the leading and trailing edges will appear. The shadow is always at the center of the clip, judging by the slow apparent motion of the few stars visible in it. https://youtu.be/JdZTDzYVLDE?t=155