The full moon rises behind the ancient temple of Poseidon at cape Sounion, south of Athens on August 1, 2023. Image Credit: AFP

Sky watchers wanting to see a once in a blue moon event should look up on Aug. 31. The super blue moon spectacle that night will be the third-largest moon that has appeared to date this year - nearing the end of the four-part supermoon series.

Who knew that the phrase, "Once in a blue moon," had ties to astronomy? It means simply something that happens rarely - like super blue moons gracing our skies.

A super blue moon occurs when a second super moon rises in a single month. The last time a super blue moon appeared was Jan. 31, 2018, and the next won't occur until Jan. 31, 2037, according to NASA ambassador Tony Rice. Before the spectacle begins, here's everything you need to know:

When and where can you see the super blue moon?

Like any other night, if you can look up and see the moon Aug. 31, you'll be able to see the super blue moon. Lucky for everyone, the show isn't a location-dependent display.

The moon won't be the only icon in the sky that night. Saturn will be a guest star, or rather planet, hanging high above the moon on its descent from opposition which occurs on Aug. 27. During opposition - the time when Earth straddles perfectly between Saturn and the Sun - the ringed, gas giant will shine.

Interested viewers will probably be able to see Saturn without a telescope but you may need some equipment if you want to see its iconic seven rings. It's also the time when Saturn, the second largest planet in the solar system, is closest to the Earth.

Why is it called a super blue moon?

Some viewers may be disappointed to know that super blue moons don't paint the moons in blue hues the way that blood moons radiate streaks of red light. The name blue moon simply means that August will be marked by two supermoons. The first supermoon of the month, a sturgeon moon, shone on Aug. 1.

Why is it so rare?

Super moons, full moons that occur when the moon is at the closest point of orbit to the Earth, can appear up to 14 percent larger and 30 percent brighter than the smallest-seeming full moon, according to NASA. Sky watchers can see four supermoons each year: They always happen consecutively and roughly 29.5 days apart.

The last of the year's supermoon series, the fall harvest moon, will rise Sept. 29.