By Terry Eliasen, Meteorologist, WBZ-TV Exec. Weather Producer

BOSTON (CBS) — Huge “heads up” for this weekend. . . We have an opportunity to see a total lunar eclipse Sunday night!

In fact, the entire eastern half of the country will be in the “path of totality,” assuring a great lunar show as long as the weather cooperates. This will be our first chance to see a total lunar eclipse here since January of 2019!

First off, the basics: A lunar eclipse occurs when the Sun, Earth and Moon are lined up. The Moon simply moves into the Earth’s shadow created by the sun. Depending on where you live and the timing of the eclipse, some get to see the whole show while others may not be as lucky. This one is lining up perfectly for the Northeast.

(WBZ-TV graphic)

A lunar eclipse happens in phases.

First, the Moon enters the penumbra, which is the faint outer shadow cast by our planet. This is tough to see without a trained eye and really isn’t all that exciting. You may be able to notice a faint shadow on the left side of the Moon beginning around 10:10 p.m. Sunday night.

(WBZ-TV graphic)

The real show starts when the moon enters the umbra, the true shadow of the Earth. This begins on the lower left corner of the Moon at 10:28 p.m. This is the beginning of a nearly three-and-a-half hour journey the Moon will take through the umbra!

The next phase. . . totality. The total lunar eclipse will last about 85 minutes and begin at 11:28 p.m. The coolest part of the whole thing is that the Moon does not completely disappear under total eclipse. Instead it turns a coppery-red because of a refracting of sunlight around the Earth.

The Moon will completely exit the umbra at 1:55 a.m. (Monday morning) and the penumbra at 2:12am. Show over.

The biggest wildcard, of course, is the weather. It is a bit early to tell how much cloudiness may or may not be around Sunday night. I do think it is likely that, given the increasing humidity, we will have to deal with some cloud obstruction in some areas. You’ll have to stay tuned for updated forecasts throughout the week. At least it looks warm!

If by chance the clouds do ruin the show, we won’t have to wait too long for another lunar eclipse. Next one arrives in the early morning hours of November 8th, this year.

Follow Terry on Twitter @TerryWBZ