Rare blue supermoon will appear this week. When and where to view it

A blue supermoon only occurs “once in a blue moon” — roughly once every decade or so — and the rare celestial event will peak tonight, per The Old Farmer’s Almanac .

During the blue supermoon, the moon will appear roughly 6% larger than normal and nearly 13% brighter than normal, per CBS News . The event won’t happen again for more than a decade.

So, how can you view the blue supermoon? What is a blue supermoon?

Here is everything you need to know about the blue supermoon event this August.

What is a blue supermoon?

A blue supermoon is a rare celestial event that occurs when a blue moon and a supermoon coincide — resulting in an extra bright, extra large full moon.

So, what is a supermoon? A supermoon happens when the Earth is closest to the moon while the moon is also full.

According to NASA , “The Moon travels around our planet in an elliptical orbit, or an elongated circle, with Earth closer to one side of the ellipse. Each month, the Moon passes through the point closest to Earth (perigee) and the point farthest from Earth (apogee). When the Moon is at or near its closest point to Earth at the same time as it is full, it is called a ‘supermoon.’”

A blue moon happens when there is a full moon twice during during a single month.

“The Moon’s cycle is 29.5 days, so just a bit shorter than the average length of a calendar month. Eventually that gap results in a full moon happening at the beginning of a month with enough days still remaining for another full cycle ― so a second full moon in the same month,” per NASA .

“In other words, a full moon that happens on the 1st or 2nd of a month will probably be followed by a second full moon on the 30th or 31st.”

Does the moon actually turn blue during a blue moon?

No. The moon won’t turn blue during a blue moon. It is just the term used to describe the rare event.

On rare occasions, the moon can appear to look blue as a result of volcanic erputions or intense wildfires, according to the Smithsonian .

In June 1991, Mount Pinatubo erupted in the Philippines, triggering the moon to appear greenish-blue in some areas around the world.

How often is a blue supermoon? Is it rare?

Super blue moons typically occur once every 10 years — but they can be as irregular as every 20 years, according to NASA .

The next blue super moons won’t occur until 2037 and will arrive in a pair. They are expected in January and March 2037.

Supermoons are more common and occur around three to four times every year, per NASA . About 25% of full moons are supermoons, but just 3% of full moons are blue moons.

A blue moon happens roughly every two to three years, per NASA .

When is the blue supermoon in August?

The next blue supermoon will occur on Monday, Aug. 19.

It will reach its peak at 12:26 MDT on Monday afternoon, but the moon will appear full for three days — from Sunday morning through Wednesday morning, per NASA .

Where can I see the blue supermoon?

Anywhere!

Supermoons, including a blue supermooon, are visible with the naked eye and do not need any special equipment or specific location to view. If skies are clear, you should be able to view the blue supermoon from anywhere.

“It’s bright enough that you don’t need to go anywhere special,” Shannon Schmoll, director of Abrams Planetarium at Michigan State University, told CNN .

There is a three-day window during which the blue supermoon will be visible to viewers.

“There’s really three days where the full moon is going to be most beautiful,” Noah Petro, lab chief of NASA’s Planetary Geology, Geophysics and Geochemistry lab, told CNN . “The thing about these super moons is because they’re so much closer, they’re also brighter. ... You’ll be treated to this beautiful sight in the sky, which is our moon hovering off in the distance.”

When is the next supermoon?

There will be three more supermoons before the end of the year. The next supermoon will occur after sunset on Tuesday, Sept. 17, and it will be a harvest supermoon, per The Farmer’s Almanac . A Harvest moon is the full moon that occurs closest to the fall equinox.

The last two supermoons of this year will occur on Thursday, Oct. 17 and Friday, Nov. 15, per Space .