Environment & Science

Mini Moon: 5 cool facts about the year's smallest full moon

The moon is seen over Dresden, Germany.
The moon is seen over Dresden, Germany.
Arno Burgi/DPA /LANDOV

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Thursday night, the world will see the smallest looking moon of the year.

It's been dubbed the "mini moon," by astronomers at the Griffith Observatory.

Mini moons are the opposite of the much-hyped supermoons, when our celestial companion appears brighter and larger than normal.

The phenomenon has been widely reported by KPCC and others.

Griffith Observatory Director Ed Krupp said that got him thinking: "Wait a minute, the moon isn’t just biggest at some point in the year... it’s also smallest."

And thus, the "mini moon" was named. Here are some fun facts about this yearly event:

1. All this fuss stems from the fact that the lunar orbit is elliptical

Since the moon does't fly around the Earth in a perfect circle, sometimes it is closer and sometimes it is further from us.

When a full moon coincides with a close pass, it's called a supermoon. When a full moon happens during the furthest pass, that is a mini moon, said Krupp.

The difference between the two moons is about 30,000 miles, or roughly four times the Earth's diameter.

2. The mini moon is actually smaller and dimmer in the sky

When the moon is furthest away it appears about 8 percent smaller in the sky than an average full moon. It will also be about 15 percent less luminous.

Don't expect to notice the difference on your evening walk though, said Griffith Observatory's Krupp.

He explained that the unaided probably can't see the difference between a mini moon and a more common moon.

3. The tides can tell the difference between a mini moon and a supermoon

According to Michelle Thaller with NASA’s Goddard Spaceflight Center, supermoons and mini moons can have an effect on the world's oceans.

Tides during a sueprmoon could be about one inch higher and lower than normal due to a slightly increased gravitational pull, she pointed out.

Likewise, you can expect slightly less tidal effect during a mini moon.

4. The term "supermoon" is believed to have been coined 30 years ago by an astrologer

Recently, the media has been all over the supermoon phenomenon. However, the term dates back to 1979 when astrologer Richard Nolle coined the phrase.

Astronomers prefer to call them "perigean full moons," but that name isn't as catchy. Griffith Observatory's Ed Krupp thinks the term supermoon caught on because it's easier to tweet, hashtag and mention on Instagram.

"I think people are trying to draw attention to their websites," he joked.

Still, he says if the term gets people to pay attention to the sky then it's a good thing.

5. Humans have known about supermoons and mini moons for centuries

Krupp says the names may be new, but the idea isn't.

He says records show that people hundreds of years ago developed ways to look at and measure the size of the moon in the sky.

He explained that they were able to see changes in the moon's apparent size.

"So this is not a brand new discovery." 

New or not, it's a fun excuse to discuss the science of the moon. To see the mini moon Thursday, simply find a dark place and look up.

Even a slightly small full moon should be easy to spot in the sky.