See Full Blood Lunar Eclipse, Century’s Longest, In Massachusetts

BOSTON, MA — A partial lunar eclipse will be visible overnight from Thursday into Friday. The full frost moon will turn red, and since the partial eclipse will last three hours, it will be the longest lunar eclipse of the 21st century, according to NASA.

Usually, light from the sun paints the face of the moon a grayish-white. But when the eclipse peaks around 4 a.m. Eastern Time on the 19th, our planet will block 98 percent of the sun’s light from reaching the moon’s surface, washing it in a reddish hue.

Related: 2021 Guide To Meteor Showers And Other Celestial Events

A partial lunar eclipse occurs when the moon passes through Earth's partial shadow, or penumbra, and only a portion of it passes through the darkest shadow, or umbra.

A total or nearly total lunar eclipse often is called a “blood moon” for this reason. The November full moon, with or without an eclipse, is also called the full frost moon, sometimes called a full beaver or dark moon. All were terms used by Native American tribes, who gave distinctive names to the moons to mark the season. The frost moon is the last full moon of autumn.

Although the eclipse lasts about 3½ hours from start to finish, most of the action takes place in a 2-hour span. People in all 50 states will be able to watch it.

Here on the East Coast, the eclipse will peak from 2 a.m. to 4 a.m. Unfortunately, the forecast isn't looking great. The National Weather Service predicted rain starting Thursday night and continuing until about 7 a.m. Friday.

Even if you can't see it yourself, you can watch a livestream of the lunar eclipse.