Super Blood Moon and Lunar Eclipse 2021: When to Watch

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Night owls in California and other points out west are in for a treat on May 26 as the moon enters Earth’s shadow and turns a blood red color during a total lunar eclipse, the first in more than two years visible from the United States.

And if you hear anyone calling this a super blood moon, that’s because the moon will also line up in its closest approach to our planet, an event some call a supermoon.

“You’re actually getting to see the solar system working, and Newton’s laws of gravity in operation before your own eyes,” said Edwin Krupp, director of the Griffith Observatory in Los Angeles.

This month’s event will be visible primarily from Australia, East Asia, islands in the Pacific and the Western Americas. People on the West Coast of the United States, from Southern California up through Washington State, can expect the action to commence around 1:47 a.m. Pacific time on May 26.

In the beginning, the moon will enter only Earth’s outer shadow, called the penumbra. Any changes to the lunar surface will be subtle at first, Dr. Krupp said.

After sailing along over the next few hours, the moon will travel deeper into the shadow, at which point it will look as if something took a bite out of it. During this phase, it will begin turning reddish. This will start around 2:45 a.m. Pacific time.

At 4:11 a.m., the moon will fall completely within Earth’s inner umbral shadow and its full face will become a deep, dark red. The quirks of the moon’s orbit mean this total eclipse will be relatively short, lasting about 14 minutes and ending by 4:25 a.m. Pacific time. Some total lunar eclipses go for nearly an hour.

But the eclipse isn’t over and sky watchers can enjoy seeing the process reverse itself as the moon passes out of Earth’s umbra and penumbra, gradually returning to its normal self until sunrise, at which point it will sink below the horizon for West Coasters.

Astrophotographers in the path of the eclipse may want to try setting up a telephoto lens on a tripod and vary the exposure at a few different shutter speeds to get the best shot, Dr. Krupp suggested.

A cellphone camera will usually make the moon appear quite small, he added, but keen observers can usually play with their phone’s settings to get a nice image.

Sorry to say, no.

As a consolation for those elsewhere in the country, the Griffith Observatory is hosting a live feed of the eclipse on its website from 1:45 a.m. to 5:50 a.m. Pacific. That means people in the Eastern time zone who wake up early enough can watch some of the show online.

Lunar eclipses occur when our planet comes between its two major heavenly companions, the sun and moon. Moonglow is actually reflected sunlight and so the lunar surface gradually darkens as the moon falls into Earth’s long shadow.

Sometimes, the moon’s celestial movements cause it to only graze part of our planet’s shadow, leading to partial lunar eclipses, which are often difficult to see. But the event later this month will see our natural satellite totally obscured by Earth’s bulk.

During such occurrences, a small amount of sunlight gets lensed around the edges of our planet. Earth’s atmosphere filters out everything but the longer, redder wavelengths, which are projected onto the moon. The coppery light — a combination of all the world’s sunrises and sunsets — creates the moon’s scarlet color during a total eclipse.

“It’s quite a spectacle to behold,” said Madhulika Guhathakurta, an astrophysicist at NASA’s Goddard Spaceflight Center in Greenbelt, Md.

The moon’s orbit is not a perfect circle around Earth but rather an ellipse, so sometimes it will be closer and farther from our planet. This month’s supermoon should make our natural satellite appear about seven percent larger and brighter than usual in the sky, though most people will have a hard time telling the difference.

When the moon is close to the horizon, it tends to appear extremely big, a well-known optical illusion that has so far defied complete explanation. Some people hear about supermoons, witness this effect, and believe they have seen something special. But the two are unrelated, Dr. Krupp said.

Supermoons lining up with lunar eclipses aren’t uncommon. The most recent super blood moon was on Jan. 21, 2019, and the next is May 16, 2022. The fact that headlines have focused on creating fun names such as the “super flower blood moon” for this month’s eclipse “is strictly a product of the internet age,” Dr. Krupp said. “We are paying attention to celestial events in far more detail than before.”

But in that sense, it is almost a return to an earlier era, when the sky had much more meaning to everyday people’s lives.

“I have no quarrel with the digital age bringing attention to things that would pass by without notice,” he added.