In the early hours of Monday a full Moon passed into Earth’s shadow in space, with those in North America, Australia and parts of Asia having the best view.
For much of the world it was merely a regular full Moon, though the sight of it rising in the east as a temporarily muted orange orb remains one of the most underrated in nature.
Known in November as either the “Beaver Moon” or the “Frosty Moon,” a full Moon is 100% illuminated by the Sun for just a moment each month when it’s positioned on the “other side” of Earth to the Sun.
However, the Moon appears to be full to onlookers for a night or so either side of that global moment.
What was unusual about Monday’s full Moon is that for a few hours it didn’t receive the Sun’s light directly.
All planets cast a shadow, and Earth’s stretches 870,000 miles/1.4 million km into space. When the Moon is in its full phase—i.e. the Sun, Earth and Moon are lined-up—our satellite occasionally passes through Earth’s shadow.
Earth has two shadows; its outer, fuzzy penumbral shadow and its inner, darker and redder umbral shadow. On Monday, November 30, 2020 about 83% of the Moon passed through Earth’s penumbra to cause a penumbral lunar eclipse.
Monday’s celestial event was the first of two successive “Beaver Moon Eclipses.” A partial lunar eclipse is set for November 19, 2021.
It happened as China’s Chang’e 5 spacecraft orbited the Moon while preparing to land. Although official details are scant, it appears that Chang’e 5 could be about to land on the lunar surface and begin its mission; to collect more moon rock and lunar soil that any mission since NASA’s Apollo 17 mission in 1972.
The penumbral lunar eclipse also lined-up something special for two weeks’ time. The path of the Sun through our sky, and the orbit of the Moon around the Earth, are not aligned. There’s about a 5º difference.