Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2021 November 25
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At the Shadow's Edge
Image Credit & Copyright: Jean-Francois Gout

Explanation: Shaped like a cone tapering into space, the Earth's dark central shadow or umbra has a circular cross-section. It's wider than the Moon at the distance of the Moon's orbit though. But during the lunar eclipse of November 18/19, part of the Moon remained just outside the umbral shadow. The successive pictures in this composite of 5 images from that almost total lunar eclipse were taken over a period of about 1.5 hours. The series is aligned to trace part of the cross-section's circular arc, with the central image at maximum eclipse. It shows a bright, thin sliver of the lunar disk still beyond the shadow's curved edge. Of course, even within the shadow the Moon's surface is not completely dark, reflecting the reddish hues of filtered sunlight scattered into the shadow by Earth's atmosphere.

Notable APOD Submissions: Lunar Eclipse of 2021 November 19
Tomorrow's picture: pixels in space


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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