Night Sky for May 2021

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U.S. Navy

Featuring The Super Blood Moon Eclipse

Bob Berman
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Here’s the May 2021 guide to the night sky. Check out the top 3 things to see in the night sky in May, including some pretty planet pairings, a total lunar eclipse, and the last supermoon of the year. It's being called the Super Blood Moon Eclipse! See more information and viewing tips.

Sky Watch May 2021

by Bob Berman, as featured in The Old Farmer's Almanac.

All five visible planets are out in May. Only Mars, however, appears in the darkness of night; look to the west. The morning planets are Jupiter and Saturn.

1. May 3 to 5: Predawn Planets and a Meteor Shower

In the predawn east on the 3rd, Saturn is to the upper left of the crescent Moon. On the 4th, Saturn forms a triangle with Jupiter and the Moon. Then on the 5th, Jupiter—which enters Aquarius this month—floats above the crescent Moon. See the Almanac's Bright Planets Calculator.

While you're observing the planets on May 4–5, look for shooting stars. The Eta Aquarids peak in the predawn hour of May 5. In the Northern Hemisphere, we expect 10 meteors per hour. The comet responsible for the Eta Aquarids shower is Halley’s Comet. See more viewing tips for meteor showers.

2. May 12 to 15: Evening Planets and a Crescent Moon

Watch the crescent Moon at nightfall from May 12 to 15! Look west—very low on the horizon—about a half an hour after sunset local time. You'll need an unobstructed view free of nearby trees and buildings such as the beach, open plains, or high up on a mountain or building.

  • On Wednesday, May 12, look first for that slender Moon in the west. To the right is Venus, and Mercury is above them both. Further up the sky dome is bright Mars. 
  • On Thursday, May 13, the Moon is higher in the sky, now just to the left of Mercury in a close conjunction, an easy 15 degrees high.
  • On Friday, May 14, the Moon has passed Mercury on its way to Mars. Venus is low in the sky but you can spot all three of the planets plus the Moon in a single view.
  • On the 15th, the crescent Moon is next to planet Mars.

3. May 26: Total Lunar Eclipse (Blood Moon)

There will be a total lunar eclipse early on the morning of Wednesday, May 26. This eclipse is only partially visible from North America. The best views will be from western North America; and the eclipse will also be visible from Hawaii. The Moon will enter the penumbra at 4:46 A.M. EDT (1:46 A.M. PDT) and umbra at 5:45 A.M. EDT (2:45 A.M. PDT). It will leave the umbra at 8:53 A.M. EDT (5:53 A.M. PDT) and penumbra at 9:51 A.M. EDT (6:51 A.M. PDT). See 2021 eclipse information.

A total eclipse of the Moon happens when the Earth completely covers the Moon with its shadow.  This only happens during a full Moon when the Earth comes between the Sun and the Moon and all three (Sun, Earth, Moon) are perfectly aligned.

Some folks will call a total lunar eclipse of the Moon a "Blood Moon." Why does the Moon appear reddish? Remember that the Moon does not have any light of its own—it shines because its surface reflects sunlight. But only the longer lightwaves (red) still reach the Moon after being refracted by the Earth's atmosphere; the rest of the shorter waves are filtered out.

Adding more interest, May's full Moon, which the Almanac refers to as the "Full Flower Moon", is the last and biggest "supermoon" of 2021. See the Almanac's Guide for May's Full Flower Moon!