Super Snow Moon To Rise With Chance Of Snow Showers In PA

EASTERN PENNSYLVANIA — There's something very magical in this weekend's forecast. Or should we say, there's a chance of something very magical in the forecast.

The full moon that will rise over Pennsylvania skies this weekend is the "snow moon," which is also a supermoon. And there's a chance of snow showers at the super snow moon's peak, according to forecasters.

The snow moon will reach peak fullness at 2:34 a.m. on Sunday. There's a slight chance we'll see some snow showers overnight Saturday into Sunday, according to the National Weather Service's Thursday forecast. The chance of snow showers is slim — just 20 percent — and no accumulation is expected, however.

Even without the snow showers, the moon should still be beautiful.

But there's a bit of a debate about whether this weekend’s “snow moon” is actually a supermoon.

A supermoon is this: A supermoon happens when the moon’s closest approach to Earth — scientifically, when the moon is at perigee — in its monthly elliptical orbit coincides with a full moon. It isn’t actually any bigger, though it appears to be up to 30 percent brighter and 14 percent larger

A full moon is this: A full moon is the lunar phase when the Earth is exactly 180 degrees opposite the sun and appears fully illuminated from our perspective on Earth.

And a snow moon? It’s a full moon that occurs during wintery February.

You probably don’t want to — and shouldn’t — stay up half the night to see the super snow moon. At peak fullness, it will look like a glaring orb in the sky, and is much more impressive as it hugs the horizon around sunset on Saturday and sunrise on Sunday. Actually, the moon is going to look big and bright on Friday and Monday, too.

The National Weather Service’s weekend forecast for Eastern Pennsylvania calls for mostly sunny skies Saturday. On Saturday night, there's a chance of snow showers after 1 a.m. Otherwise, it will be mostly cloudy through daybreak, with a low around 29.

Back to the debate over whether the February full snow moon is actually a supermoon: It depends on whom you ask.

Don’t ask the International Astronomical Union. That group, which names and defines things in astronomy, hasn’t concerned itself with the last decade’s hype over supermoons. The group’s website is full of useful information about the importance of the moon, though.

But you can ask retired NASA astrophysicist Fred Espenak, who calls himself “Mr. Eclipse” and says the February snow moon is a supermoon. Not only that, Espenak says it’s the first, and the smallest, of four consecutive supermoons, with the last one in May.

Hold on, says Richard Nolle, the Tempe, Arizona, astrologer who coined the word “supermoon” to describe a full moon at perigee. He says the February full moon isn’t a supermoon. Until Nolle “branded” the supermoon in 2011, astronomers called the full moon that coincided with perigee a “perigean full moon,” and it passed without notice.

Nolle and Espenak agree the March and April full moons will be supermoons, but disagree on whether May’s and February’s full moons will look bigger and brighter than usual when appearing over the horizon.

The disagreement between the two men stems from how Nolle defines a supermoon. It’s complicated, and not requisite knowledge to sit back and gaze at the moon; but if you’re curious, Earthsky.org has a detailed explanation.

The reason the moon appears bigger and brighter is a bit puzzling, but scientists suggest it’s a trick of the mind — a “moon illusion.” It could be the brain is just wired to compare the size of the moon to other objects near the horizon, or to view things near the horizon as larger than those in the sky, according to Space.com.

And despite all the hype surrounding supermoons, it’s going to be hard for the naked eye to discern the difference “unless you’re a very careful moon-watcher,” Sky & Telescope magazine senior editor Alan MacRobert said in 2016.