5 things to know about Saturday’s supermoon

The term "supermoon" was coined by astrologer Richard Nolle, not an astronomer. (Source: PBS.org)

Brtish astronomer Gemma Lavender says Nolle's claims that the moon's closeness to the Earth can trigger earthquakes, volcanoes and tidal floods are unfounded.

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Nevertheless, the term has become more popular with the general public in recent years.

>> UPDATE: Photos: Supermoon lights up the sky around the world

>> UPDATE: Must-see: Stunning supermoon shines in the night sky

WHEN ARE THIS YEAR’S REMAINING SUPERMOONS?

There were three supermoons earlier in the year, and there are three supermoons remaining in 2015: August 29, September 28 and October 27.

>> Watch: When to catch this Fall’s 3 supermoons

WHAT IS A SUPERMOON?

Because the moon has an elliptical orbit, instead of revolving around the Earth in a perfect circle, there is a time when it is farthest from us — the apogee — and a time when it is closest — the perigee.

"What skywatchers are most interested in is perigee, the date and time when the moon is closest to Earth." (Source: Discovery.com)

PERIGEE IS SUNDAY

So, the perigee is the point when the moon is closest to the Earth.

"This month, perigee occurs on Sunday, Aug. 30, at 11 a.m. EDT (1500 GMT), about 18 hours after full moon. At that time, the moon will be 222,631 miles (358,290 kilometers) away from Earth."(Source: Discovery.com) 

SUPERMOON ACTUALLY OCCURS 18 HOURS AFTER FULL MOON

This month's perigee occurs Sunday, Aug. 30, at 11 a.m.(EDT). That's about 18 hours after the Saturday night full moon. So the August supermoon is not quite full.

COMING UP: SEPTEMBER SUPERMOON HAS IT ALL

Although the full moon and perigee don’t exactly overlap this month, the supermoon next month — on Sept. 28, 2015 — will coincide with the full moon, making it the biggest and closest moon of the year.

Not only is the September supermoon a full moon, it's also known as the Harvest Moon.