A deep partial eclipse of the Moon for early risers

The partial eclipse of the Moon on November 19, 2021 will be very similar to the one in September 2015 that can be seen in this photo.
Credit: Michael Seeley
L’éclipse partielle de Lune du 19 novembre 2021 sera très similaire à celle de septembre 2015 que l’on peut observer sur cette photo.
A deep partial eclipse of the Moon for early risers

Stargazers will get to observe a beautiful partial eclipse of the Moon in the wee hours of November 19. For the occasion, the Moon well penetrate deeply into the Earth’s umbra, producing a partial lunar eclipse, but which will be almost total.

The entire eclipse will be observable everywhere in North America, in the Pacific and in the Far East.

How does a lunar eclipse happen?

It happens when the Moon crosses through the Earth’s umbra, or shadow. When the Moon enters entirely into the umbra, we say that the eclipse is total.

During a total eclipse, the Moon does not entirely disappear, but rather takes on reddish hues. With sunlight being refracted by the Earth’s atmosphere, only red light reaches the lunar disc and illuminates it during the eclipse’s totality phases.

In a partial eclipse, only a portion of the lunar disc enters the Earth’s shadow. In this case, the part in the shade grows dark, because the contrast in brightness between the part lit up directly by the Sun and the part eclipsed is too great.

Position of the Moon in the sky during the eclipse.

Position of the Moon in the sky during the eclipse.
Assembly: Space for Life (André Grandchamps)

Lunar eclipses always take place when there’s a full Moon. However, the Moon’s orbit is tilted by five degrees compared to the Earth’s around the Sun. Most of the time, the Moon passes above or below the Earth’s shadow during a full Moon. The perfect alignment for observing eclipses happens only once or twice a year.

The circumstances of the eclipse on November 19, 2021

The eclipse will get started at 2:18 in the morning when the Moon begins to enter the Earth’s umbra. It will reach its maximum at 4:03 a.m., when 97.4 percent of the lunar disk will be in the Earth’s shadow. The partial eclipse will be so deep that we’ll be able to see the Moon turn a reddish color, as it does in a total eclipse. Only a very thin crescent will still be illuminated by the Sun. The phenomenon will end at 5:47 a.m.

Circumstances of the lunar eclipse of November 19, 2021.

Circumstances of the lunar eclipse of November 19, 2021.
Space for Life (Marc Jobin)

The Pleiades as a bonus

To add to the beauty of the spectacle, during the eclipse the Moon will be situated just under the Pleaides. Take advantage of the occasion to observe this magnificent cluster of young bluish stars, which will produce an interesting contrast with the red-tinged Moon. Through binoculars the Pleaides star cluster reveals itself in all its beauty.

At the peak of the eclipse, seen from Montréal, the Moon will be at an altitude of 29° westward. In other words, we’ll need a clear western horizon to have a good view of the end of the eclipse.

So now all we have to do is hope that the weather will be favorable enough for us to admire this celestial spectacle!

For more information on observing planets, constellations, and other astronomical phenomena
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