Once in a blue moon? Try twice in 2018

WLUK image.

MENASHA (WLUK) -- On Jan. 1, we saw the first full moon of 2018, and on Jan. 31, we'll be treated to another full moon.

The second of two full moons in one month is what's known as a blue moon.

And the phrase "once in a blue moon" has a different meaning this year.

At the Barlow Planetarium at the University of Wisconsin-Fox Valley, Director Alan Peche explained to FOX 11 News that when you say "once in a blue moon," you're really saying "once every two and a half years."

"There's about 40 or so blue moon situations per century, so that means we typically have a a blue moon every two and a half years or so," he said.

And in 2018, there will be an even more rare phenomenon: two blue moons in one year.

"We had a full moon yesterday on Jan. 1. In about 29 and a half days another full moon comes around so we get one right at the end of January and then the next one takes another 29 and a half days, however, February is only 28 days. So the next full moon's at the beginning of March," Peche explained.

That will be March 1, with one more on March 31. The last time that happened was in 1999.

On top of that, Peche told FOX 11, the full moon on Jan. 31 will be special.

"It's going to be in a position where it's gonna enter the Earth's shadow. So we're gonna have a total lunar eclipse," he said.

According to, a total lunar eclipse during a blue moon hasn't happened for at least 150 years.

Peche told us a lunar eclipse is also known as a blood moon, because it takes on a reddish color.

"The only sunlight is coming through the Earth's atmosphere and the Earth's atmosphere, because we can tell right now the sky is blue, the Earth's atmosphere scatters blue and only red can penetrate through the atmosphere and continue onto the moon and make the moon red," he said.

Unfortunately, Peche explained, you'll have to travel if you want to see the full lunar eclipse.

"Here in Northeast Wisconsin it's setting just as it's getting interesting. So people out west will be able to see it a little bit better," he said.

Regardless, Peche advises to try to enjoy these lunar events.

"Go out, look, watch it, observe how it changes throughout the night," he said.

Because they only come around once in a ... well, you know.

The next time we'll see two blue moons in one year will be 2037.

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