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August continues to be an exciting month for stargazers. Shortly after the peak of the Perseid meteor shower last week, the first of the year’s four consecutive supermoons will rise on August 19. The rare cosmic combination of a supermoon and a blue moon peaks at 2:26 p.m. ET on Monday.
The last time this lunar phenomenon occurred was in August 2023. The next super blue moons are expected in January and March 2037. About a quarter of all full moons are supermoons, while only 3% of all full moons are blue moons.
So-called supermoons are said to be the biggest, brightest lunar events of the year. The moon’s orbit around Earth is not a perfect circle, but an elliptical path. Scientists call the closest point the moon comes to Earth — an average distance of about 226,000 miles (363,300 kilometers) — during its 27-day journey the moon’s perigee, according to NASA.
There are several definitions for supermoons, said Noah Petro, lab chief of NASA’s Planetary Geology, Geophysics and Geochemistry lab. However, a full moon within 90 percent of its perigee is often described as a supermoon, he said.
When the Moon is closest to Earth in its orbit, it can appear up to 14 percent larger and 30 percent brighter than when it is at its furthest point from the planet, called apogee, about 250,000 miles (405,500 kilometers) from Earth.
While this perceived increase in size may be subtle, NASA describes a supermoon as noticeably brighter than other full moons during the year. It can be hard to tell the difference, but a supermoon has a significant impact on the Earth, leading to higher than normal tides due to its proximity.
Visibility of the supermoon
Supermoons are visible to the naked eye and do not require a specific location to view them. Throughout the night, the moon will rise higher until just before sunrise.
Shannon Schmoll, director of the Abrams Planetarium at Michigan State University, says you can see the moon if the sky is clear of clouds and you have a clear view.
“It’s bright enough, you don’t have to go out there specifically,” and it’s visible right after the sun sets, she said.
Petro said the beauty of these full moons is that if clouds block the view, you can watch them any night before or after the peak of the full moon.
“So there are actually three days when the full moon is at its most beautiful,” he said.
“The thing about these supermoons is that they’re so much closer, they’re also brighter.” He noted that if it’s a clear night, you can notice the change in brightness outside. “You’re treated to this beautiful sight in the sky, which is our moon floating off in the distance.”
Because supermoons are 30% brighter than average full moons, they are easier to see.
“It’s getting a little bit brighter and that’s always a good excuse to get outside and appreciate the universe, our place in it, and what we can see from Earth,” Schmoll said.
What are blue moons and sturgeon moons?
Despite its name dating back to 1528, the moon will not appear blue, wrote NASA’s Gordon Johnston.
“Only when there is a lunar eclipse does the moon appear to change color,” Petro said.
As with supermoons, blue moons have different definitions: monthly and seasonal.
Schmoll explained that “on average we have one full moon per month, but because most months are slightly longer than a lunar cycle, that means that if we have a moon at the beginning of a month, we can have another full moon at the end of the month. Sometimes that’s called a blue moon.”
A seasonal Blue Moon is often defined as the third full moon of an astronomical season with four full moons.
“If you take a season, a season is about three months long. So in that time you normally have three full moons in a season, and if you have four in a season, the third of the four is the blue moon, and that’s what this blue moon is,” Schmoll said.
In the 1930s, the Maine Farmer’s Almanac began using names that corresponded to natural occurrences for the full moons, Petro said. Those names have been widely used and recognized ever since. “Sturgeon moon came about from native observations within the area,” he said.
According to the Maine Farmer’s Almanac, the Algonquin tribes, who once lived in what is now the northeastern United States, called the full moon in August the Sturgeon Moon, so named because it was an easier time to catch large fish during that season.
Upcoming Heavenly Events
When you look at the moon, look for Jupiter and Mars, Schmoll said.
Last week, the two planets were in conjunction, making them the closest together from Earth since 2018. Jupiter and Mars will likely remain fairly close together in the sky during the peak of the supermoon, Schmoll said.
And in the next month or so, expect a bright event known as a nova to take place in the Milky Way’s Corona Borealis, or the constellation of the Northern Crown. Astronomers expect T Coronae Borealis, nicknamed the Blaze Star, to explode as a binary system of a dead white dwarf star and an aging red giant collapses violently.
“There will be something that looks like a new star in the constellation for a few days to a week before it disappears from view. And this is something that happens about every 80 years,” Schmoll said. “That’s something that we don’t know exactly when it’s going to happen, but we expect it to happen,” Schmoll said.
Remaining supermoons of the year
The remaining supermoons of 2024 will occur on September 18, October 17, and November 15.
September’s supermoon will also be a partial lunar eclipse, meaning the Earth will cast a shadow over part of the moon, Petro said. “It’s a partial one, so it won’t be as obvious to a viewer,” he said.
The fullest, largest moon of the year will rise in October. “The moon will actually be about 100 kilometers (62 miles) closer to Earth on Oct. 17,” Petro said.
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