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Lunar Eclipse - Nov. 18-19, 2021

A lunar eclipse is taking place this week and is visible everywhere in Canada! Starting the night of November 18, 2021 and continuing into the early morning hours of November 19, the Moon will slowly enter the Earth's shadow until the maximum eclipse, when 97% of the Moon will be obscured.

Unfortunately for Canada, the timing isn't great (this article discusses the timing for Montreal —convert to your time zone). If you're going to observe it, the interesting part begins at 2:18 am. At this time, the Moon, which was full just a few minutes before, will appear to be missing a piece. As the shadow grows across the surface of the Moon, it will appear to shrink until the "maximum" of the eclipse. The maximum is the best part of the eclipse, which will happen at 4:03 am, when the Moon will be 97% covered by Earth's shadow. At this point, the shadowed part of the Moon will appear dark red.

Then the Moon will continue on its path along its orbit, becoming more and more visible as it leaves the shadow of the Earth. It will appear full again at 5:47 am when the eclipse is over.

The other times indicated above —1:02 and 7:03— show the start and end times of the penumbral eclipse, which is much less interesting to observe.

NOTE: Unlike a solar eclipse, a lunar eclipse is completely safe to observe directly with the eyes.

What's Going On?

Even if you can't observe the eclipse, you can take this opportunity to tell your students about it and explain the phenomenon to them.

lunar eclipse alignment Sun Earth Moon
Alignment of the Sun, Earth and Moon during a total lunar eclipse. Credit: Discover the Universe

You can use a flashlight (Sun) and balls (Earth and Moon) to model eclipses in the classroom. Shine the light on the Earth-ball and make the Moon-ball go around the Earth. When the Moon-ball enters the Earth's shadow, it's a lunar eclipse!

This activity might make it seem like eclipses should happen more frequently because your model is not to scale; you can produce eclipses with each orbit of your Moon-ball (whenever it circles the Earth-ball). In reality, eclipses are less frequent and occur only every six months or so.



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