If you enjoyed the US total solar eclipse last year, then we’ve got a treat for you at the start of 2018. There’s going to be a total lunar eclipse on January 31, and it coincides with a “Blue Moon” for the first time since 1866.

A lunar eclipse occurs when the Moon passes directly into Earth’s shadow, known as the umbra. This occurs when the Sun, Earth, and Moon are aligned.

What makes it impressive is that in the umbra, the Sun’s light is being refracted to its fullest by our atmosphere, pushing it towards the red end of the spectrum (like at sunset or sunrise). As the Moon passes into the umbra, its surface is bathed in red light, with this event sometimes called a blood moon.

Lunar eclipses only occur during a full Moon. But this lunar eclipse will take place during a Blue Moon, which is the name used to denote the rare instance where there’s a second full Moon in a month. Thanks to Space.com, we can see that the last time a Blue Moon coincided with a total lunar eclipse was March 31, 1866. You won’t have to wait as long for the next one, though, as it’ll happen on December 31, 2028.

Blue Moons are quite rare, with the last coming in July 2015 – although we’ll get another one in March this year. The exact meaning of the name has also been muddled over time, with some historical records suggesting the term related to the seasons, rather than the calendar month. Lunar eclipses occur about two to four times each year.

In order to enjoy a lunar eclipse you will need to be in the path of totality (which lasts about 77 minutes), just like a solar eclipse. The best places to view it will be central and eastern Asia, Indonesia, New Zealand, and Australia. Parts of North America should also get a glimpse.

If you want the exact timings you can find them here in this post from EarthSky. If you get a chance, it’ll definitely be worth a look at an event that really is once in a Blue Moon.