Lunar Eclipse of the May Full Moon to Light Night Sky in Stunning Display

Stargazers are in for a special treat later this month as a total lunar eclipse is set to grace the skies in what is expected to be a stunning display.

A total lunar eclipse happens when the sun, Earth and full moon form a near-perfect line-up in space, Diana Hannikainen, observing editor at Sky & Telescope magazine, told Newsweek.

The technical word for such an occurrence is "syzygy"—a term that can be applied to the roughly straight-line configuration of three (or more) celestial bodies in a gravitational system.

When a total lunar eclipse occurs, the moon "gradually glides into Earth's central shadow, or umbra, until the entire lunar disk turns from silvery grey to an eerie dim orange or red," Hannikainen said. "As it glides back out of the shadow, it gradually returns to full brilliance."

Fortunately, observers in the United States will be among the best placed to view the upcoming lunar eclipse, which takes place over the night of May 15-16.

The total phase of the eclipse will be visible across most of the Americas—except for the northwesternmost part of the continent—the western edge of Europe, western parts of Africa, and the Antarctic.

From beginning to end—when the moon's disk first touches Earth's shadow to when it last leaves it—the whole event will last about 5 hours and 20 minutes, according to Hannikainen.

A total lunar eclipse
Stock image showing the moon during a total lunar eclipse. A total lunar eclipse is set to grace the skies in May. iStock

The event can be divided up into three stages—the first of which is known as the penumbral stage. This is when the moon enters the lighter shadow of the Earth, called the penumbra.

The partial phase (when the moon isn't fully inside Earth's shadow) occurs next and will last around 3 hours and 28 minutes. This is followed by the total phase (when the whole lunar disk is inside Earth's shadow,) which will last around 85 minutes.

"As the first stage of the eclipse gets underway—the penumbral stage—the moon has a slight, dark shading that may be hard to detect," Hannikainen said. "But as the moon's leading edge enters the umbra, the cone of Earth's shadow within which the sun is completely hidden, the shading becomes more obvious—this is the partial phase."

"During total eclipse, the last rim of the moon slips into the umbra and the moon will glow in shades ranging from an intense orange or red. Then everything happens in reverse order until the moon blazes in all its dazzling glory again."

For those located in the Eastern time zone of the U.S., the penumbral stage of the eclipse will begin at 9:32 p.m. ET on May 15 and the whole event will be over by 2:50 a.m. ET on May 16. The maximum eclipse will occur at 12:12 a.m. ET.

"Depending on where you are in the world, you may need to set your alarm so as not to miss it: in Europe and Africa, the action takes place before dawn on May 16, while in the Americas, viewers get to see the show late in the evening on May 15," Hannikainen said.

"Lunar eclipses are great events because you need absolutely no equipment to enjoy them except for your own eyes," she added. "So, the simplest thing to do is to just get out there, look up, and enjoy! You can always grab a pair of binoculars, though, if you have them, for they'll help you see the colors more vividly."

The upcoming total lunar eclipse—the first to be visible across the contiguous United States since January 2019—also coincides with what astronomers call a "perigee-syzygy," or what is sometimes popularly referred to by the non-technical term "supermoon."

A perigee-syzygy is essentially when the moon is full and at its closest point to Earth in its orbit—or its "perigee." Because the moon's orbit around our planet isn't perfectly circular, there are times when it is closer and times when it is further away.

"There isn't any specific link between perigee-syzygy moons and eclipses," Hannikainen said. "Perigee-syzygy moons occur about three to four times per year. And sometimes they will coincide with a lunar eclipse. It's not a very common occurrence, but it's not particularly rare, either. For example, the one before this one was only last year, on May 26, 2021."

Nevertheless, Hannikainen urged stargazers to check out the upcoming celestial event later this month.

"Please go out and enjoy the wondrous sight of our closest celestial neighbor glow in all shades of intense orange or red," she said. "Eclipses are a great opportunity to witness our solar system in action!"