Technology & Science

How to watch the 'blue moon' lunar eclipse

It's not often that you get two full moons in one month. Well, this month we'll not only get that, but also a lunar eclipse.

You'll have to set the alarm clock pretty early to catch it

What's coming on Jan. 31 is being called a 'blue moon,' but it's likely it'll be closer to red. (Carl Recine/Reuters)

If you live on the west coast, you're in for a rare treat in the wee hours of Jan. 31: a "blue moon" lunar eclipse.

We've come to expect a full moon every month. While that is mostly true, sometimes we get two in one month, something that is referred to as a "blue moon." But that means that the next month, February, is without a full moon. March will also have two full moons.

January's second full moon occurs on Jan. 31 — which also happens to be the day of the first lunar eclipse of the year.

On top of that, the moon will be just two days past its perigee, which is the time in which the moon is closest to earth in its monthly orbit. In popular culture, people have recently adopted the name "super moon" for the time when a full moon is at its perigee. So, some people are calling the coming lunar display a "super blue blood moon."

Why the blood?

During a lunar eclipse, there is a sun-Earth-moon alignment. Because the sun lies directly behind Earth, it refracts, or bends light. Blue light is scattered, leaving only red. The light of all the sunsets and sunrises occurring simultaneously is reflected off the moon, making it seem red.

This can be exacerbated by particles in the atmosphere, such as a volcanic eruption. It will be interesting to see if the recent eruptions in Japan and the Philippines will make this eclipse a deeper red than most.

If you're hoping to catch the eclipse, here's how you can see it. 

First, hope for clear skies. The winter months can be pretty unforgiving when it comes to cloud cover. And if you're on the west coast, good news: you get to experience the entire thing. Then, all you have to do is look to the west. 

Unfortunately, for those on the east coast, the moon will have already set by the time the eclipse begins.

During an eclipse, there are actually two shadows: the penumbra and the umbra. The penumbra is the outer, dimmer shadow, while the umbra is the darkest part. 

A combination of photos show the moon turning a reddish colour during an eclipse in Brussels, Belgium, in 2015. (Yves Herman/Reuters)

When the moon begins to pass through the umbra, we begin to notice that it looks as though something has taken a nibble out of the moon.

In the chart above, you can see when that will begin. Maximum eclipse occurs when the entire moon sits within the umbra. 

If you're up for it, you can also always try photographing the moon during the partial eclipse, but for those in Winnipeg and farther east, you'll need to be somewhere high up with an unrestricted view of the horizon.

About the Author

Nicole Mortillaro

Senior Reporter, Science

Nicole has an avid interest in all things science. As an amateur astronomer, Nicole can be found looking up at the night sky appreciating the marvels of our universe. She is the editor of the Journal of the Royal Astronomical Society of Canada and the author of several books.