August's full moon is a rare 'super blue moon.' What will it look like?

Barring pesky clouds, skywatchers will have a spectacular view of a super blue moon when it rises in the evening sky on Monday, Aug. 19.

This super blue moon is a rare event.

The "super" part of its title refers to the moon's orbit, which brings it slightly closer to Earth this month, upping its size and brightness. The "blue" part means that this is the third of four full moons this season, an unusual occurrence.

A blue moon happens once every two or three years on average, according to NASA , but a blue moon that's also a supermoon is even more uncommon. The time between super blue moons can be as much as 20 years ― but in general, 10 years is the average.

The next super blue moon will be in January 2037.

When is the super blue moon?

The moon will reach its peak fullness at 2:26 p.m. EDT on Monday, August 19, 2024. Here in the U.S., it will be below the horizon at that time. However, the moon will look plenty full when it rises in the eastern sky Monday evening. According to NASA, the moon will actually appear full for three days, from Sunday morning through early Wednesday morning.

What causes a supermoon?

The moon's elongated orbit around the Earth can sometimes cause the moon to appear larger. When the moon is full and its orbit is closest to Earth, the moon is in perigee – the technical name for a super moon.

"Different publications use slightly different thresholds for deciding when a full moon is close enough to the Earth to qualify as a supermoon," NASA says. "Because the orbit of the moon is not a perfect circle, the moon is sometimes closer to the Earth than at other times during its orbit."

Astrologer Richard Nolle defined the term "supermoon" in 1979 as "a new or full moon that occurs when the moon is at or near (within 90% of) its closest approach to Earth in its orbit."

According to EarthSky.org the next full supermoons will occur on:

• Sturgeon Moon : Aug. 19 at 2:26 p.m. EDT (Full supermoon)
• Harvest Moon : Sept. 17 at 10:34 p.m. EDT (Full supermoon)
• Hunter's Moon : Oct, 17 at 7:26 a.m. EDT (Full supermoon)
• Beaver Moon : Nov. 15 at 4:29 p.m. EST (Full supermoon)

How the moon appears super-sized

When the moon reaches its closest point to Earth, about 226,000 miles away, full moons appears much larger and brighter than other times. A supermoon will appear 30% brighter and 14% larger than a typical full moon.

What is a blue moon?

When someone uses the phrase "once in a blue moon," it implies that they're talking about an uncommon occurrence. This is true for the two definitions of a blue moon:

When there are four full moons in a single season (on this occasion, summer), the third of the four is considered a blue moon.

A second definition of blue moon — which arose from a misunderstanding of the original — is known as the monthly blue moon, referring to the second full moon in a single calendar month.

A warning about this month's full moon: It's unlikely to appear blue: Blue-colored moons in photos are usually made using special blue camera filters or photo editing apps.

After this month's blue moon, there won't be another one until May 2026.

Why is it also called the sturgeon moon?

"August’s full moon was traditionally called the sturgeon moon because the giant sturgeon fish of the Great Lakes and Lake Champlain were most readily caught during this part of summer," the Old Farmer's Almanac said.

Sturgeon fish were once found in great abundance, but their populations have declined greatly due to overfishing and habitat loss, the National Oceanic and Atmospheric Administration said.

SOURCE Space.com, NASA, EartthSky.org, BBC SkyatNightmagazine.com and USA TODAY research

This article originally appeared on USA TODAY: August's full moon is a rare 'super blue moon.' What will it look like?