A total lunar eclipse will occur on Sunday, January 20.

This "super blood wolf moon" gets its name because the eclipse will occur when the moon is full (called a wolf moon in January) and closer to Earth than normal (a super-moon). The Earth's shadow will make it appear reddish.

The lunar eclipse is slated to last one hour and two minutes.

On Sunday, January 20, the Earth will pass between the sun and moon, block light from the sun and casting a shadow on the moon.

This is a total lunar eclipse, and it will be the last one we see until May 2021 (though there will be partial lunar eclipses before then).

Total lunar eclipses are not that rare — the last one occurred in July 2018 — but this one stands out as a "super blood wolf moon."

That name is based on the eclipse's timing and the moon's position relative to Earth. Total lunar eclipses make the moon look orange-red because of the effect that Earth's atmosphere has on the sunlight that passes through it, which is why they are often called blood moons. Full moons that occur in in January are known as "wolf moons" (each month gets its own full-moon name), and this one will appear especially bright and big because the moon will be a little closer to Earth than normal — hence the label "super."

The total lunar eclipse will be fully visible to people in North America, South America, Greenland, Iceland, western Europe, and Africa. People in other parts of the world will see a partial eclipse.

According to NASA, the total lunar eclipse will last one hour and two minutes. For those on the US East Coast, the total eclipse will begin around 11:41 p.m. local time with a peak at 12:16 a.m.

During a lunar eclipse, the moon first touches Earth's outer shadow, called a penumbra, then moves into the full shadow, called the umbra. It then goes back into the penumbra.

A diagram of the Earth, moon, and sun during a total lunar eclipse or "blood moon." Shayanne Gal/Business Insider

About 80% of Earth's atmosphere is nitrogen gas, and the rest is mostly oxygen. After our atmosphere takes in white sunlight, that gas mixture scatters around blue and purple colors, which is why the sky appears blue to our eyes during the day.

During a lunar eclipse, Earth's atmosphere scatters blue light and refracts the red — a process similar to what we see during sunrise and sunset. That's why the moon appears to turn red when in Earth's umbra.

Watching a total lunar eclipse is not dangerous — unlike looking at a solar eclipse without protection — so you don't need any special glasses.