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The Supermoon Cometh: What It Is and How To See One This Weekend

Supermoon Rise over Downtown Los AngelesSupermoon Rise over Downtown Los Angeles
Composite photo of the November 13th Supermoon rising over Los Angeles in 2016.Hal Bergman—Getty Images

For as long as humans have been observing celestial movements, there has been speculation about what rare planetary events signify.

The Dec. 3, 2017 supermoon isn’t super rare — it happens about once per year — but it’s still a better-than-usual opportunity to admire the beauty and wonder of nature, make predictions about its doomsday implications, or do both while snapping the perfect shot for your Instagram feed. (In fact, NASA has some tips on how to get the best shot of the supermoon.)

It’s worth mentioning that Gizmodo science writer Ryan F. Mandelbaum makes a pretty convincing argument for why we should all look at the moon more often, even when there’s nothing super about it.

“It’s over four billion years old, it’s an incredible rock only 240 thousand or so miles away. It’s responsible for the tides and eclipses and moderating the climate. Humans literally walked on that thing,” he writes. “It’s deeply rooted in culture and religion, and you’ll join the billions of others who’ve looked at and appreciated the Moon all through history. You can’t look at the Sun, after all.”

What is a supermoon?

A supermoon is a full moon that occurs at or near the time when the moon is at its closest point in its orbit around Earth. Astronomers have a less colloquial term for it: A perigean full moon.

The term “supermoon” was coined by astrologer Richard Nolle in 1979 (though Neil deGrasse Tyson is not buying the “super” qualifier). The scientific name for this phenomenon is perigee syzygy, which signifies the placement and phase of the moon.

“Perigee refers to the moon being at its closest distance to the Earth, and syzygy refers to the alignment of multiple bodies — the moon, Earth and sun need to be aligned for us to see a full moon,” University of Arizona astronomy professor Gurtina Besla told NPR. “So it translates to the closest separation between the moon and Earth when the Earth, moon and sun are aligned.”

When is the next supermoon?

The next supermoon occurs on Sunday, December 3, 2017. It’s the only observable supermoon this year, but not actually the time when the moon has been closest to the Earth in 2017. That happened in May, during one of the three other supermoons in 2017, that coincided with new moons. And a new moon, unfortunately for astrology lovers, is impossible to see with the naked eye.

Even though the other three supermoons weren’t visible, their impact on the Earth were. They caused higher high tides and lower low tides — often called “spring tide.”

The supermoon will rise over New York City at 4:59 p.m. Sunday. Not on the East Coast? Specific moonrise times can be found at timeanddate.com. The moon looks particularly impressive as it rises for the first time. But this won’t have as small an observation window as an eclipse, which lasts only a few minutes. Professor Besla says that peak viewing time will actually be a few days later, on Monday, Dec. 4 at 3:45 a.m. EST.

It won’t appear to be as large as the record-setting supermoon, which occurred last November and was the closest the moon had been to the Earth since 1948. But it is your first and last chance to see one this year. If you’re not able to make it outside to see it in person, the Virtual Telescope Project will have a live video feed.