This week, part of the world will be treated to a rare kind of lunar eclipse, as the moon will turn red and become a so-called Blood Moon.

This month’s full moon –– the Worm Moon –– will completely enter Earth’s shadow on the night of March 13 or early morning of March 14. Unlike a solar eclipse that is only visible within a narrow stretch of a few hundred miles, the “Blood Worm Moon” will be visible in the entire Western Hemisphere, including all of North and South America and the far western parts of Africa and Europe.

But what is a lunar eclipse and what makes this month’s total lunar eclipse so special?

The answer to both questions comes down to “a little bit of luck and a little bit of geometry,” says Jacqueline McCleary, an assistant professor of physics at Northeastern University.

Read more from Northeastern Global News. 

AP Photo/Ted S. Warren