From Thursday night into Friday morning, Earth’s shadow will swallow the moon, transforming the usually pearly orb into a striking red sphere.
It’s the first total lunar eclipse in more than two years. Also known as a blood moon, the event will be most visible across the Americas, western parts of Africa and Europe, New Zealand and some of Russia.
“It’s a lovely sight to see in the night sky,” said Amanda Bosh, the executive director of the Lowell Observatory in Arizona, who has seen more than 20 lunar eclipses in her lifetime.
“I love seeing the solar system, the universe, at work,” she added.
What is a total lunar eclipse?
A lunar eclipse occurs when the sun, Earth and moon align, in that order. There are different types of lunar eclipses that depend on how deeply the moon crosses into Earth’s shadow, which is divided into an outer part, the penumbra and the umbra, the innermost section.
A total lunar eclipse, when the entire moon slips into the umbra, is by far the most dramatic variety. Earth’s shadow envelops the face of the moon, causing it to shine scarlet. This happens because sunlight spilling over the edges of Earth and lighting up the lunar surface must first travel through our atmosphere, which more readily scatters blue wavelengths of light. Redder wavelengths pass through, creating the blood-moon effect.
According to Dr. Bosh, the exact shade of red during a lunar eclipse can vary. Clouds and recent natural disasters — like dust storms or volcanic eruptions, which leave particles in the air — can make the moon appear more crimson.
Less visually striking is a penumbral eclipse, when the moon grazes through the outer part of Earth’s shadow. This causes the moon to dim so slightly that it can be difficult to notice.
When only a portion of the moon recedes into the innermost umbra, it creates a partial eclipse, which looks like a bite has been taken out of the lunar surface.
When will this eclipse occur?
There are several phases of a total lunar eclipse. According to the United States Naval Observatory, the event will occur over about six hours across Thursday and Friday.
The moon will begin to creep into Earth’s penumbra at around 11:56 p.m. Eastern time on Thursday. At 1:09 a.m. on Friday, the moon will enter the umbra, during which a growing portion of its surface will be obscured from view. According to Dr. Bosh, the moon will appear more red as the partial phase elapses.
Totality, when the entirety of the moon is engulfed in the darkest part of Earth’s shadow, occurs at 2:25 a.m. and lasts for just over an hour.
Then the lunar surface will begin to brighten white again as the moon glides out of the umbra, a phase that lasts until 4:48 a.m. Eastern time. The final leg of its journey, through the penumbra, finishes at 6:01 a.m.
How can I see the eclipse?
Anyone on the night side of Earth will have the opportunity to see the lunar eclipse, but how much you can see depends on your location.
Skywatchers in most of North America and the western half of South America can witness the entire event. But in other places, people may just catch the eclipsed moon rising or setting in the sky.
No special equipment is needed for this cosmic sight. “It’ll look just as beautiful with your eyes” than it would through a telescope, said Dylan Short, a telescope specialist at Lowell Observatory. Decent photographs can be taken with a cellphone, he said, or with a simple D.S.L.R. camera that uses a lens with a long focal length. Images of the moon can also be captured through the eyepiece of a telescope.
In many cities, local stargazing groups and planetariums are hosting watch parties. Another option is to view a live broadcast of the lunar eclipse online.
Will weather affect my viewing?
Although a winter storm is barreling across the United States, forecasters say sky viewers have a shot at seeing the eclipse in several areas, including portions of Florida, the central and southern Plains, West and South Texas, the Ohio Valley into the Appalachian Mountains, and a sliver of the desert Southwest.
But in other parts of the country, including the East and West Coasts, clear views may be more difficult to come by.
If you do see clouds in the sky during the eclipse, keep in mind that the event unfolds over several hours. It may be worth looking again later, especially if those clouds are thin or seem to be moving.
When will the next eclipse occur?
Lunar eclipses can happen several times a year, though not all of them reach totality. According to NASA, the next total lunar eclipse will occur in September, most visible in Asia and parts of Europe, Africa and Australia.
There will be another total lunar eclipse next March, followed by a partial lunar eclipse later in August.
Lunar eclipses also occur paired with solar eclipses. On March 29, this lunar eclipse’s partner, a partial solar eclipse, will be visible in parts of North America and Europe.
Amy Graff contributed reporting.
