Exactly Where And When To Watch Tonight's Lunar Eclipse

There's a lunar eclipse tonight.

Consult the map above to find out if and when the eclipse will be visible in your region of the world.

For those in Canada (with the exception of Eastern Canada) and the United States, the eclipse will already be in progress when the moon rises. Skygazers in Europe, Africa, and Western Asia can see the entire event during the middle of the night, while Eastern Asia will miss the end of the eclipse because of moonset.

A lunar eclipse happens when the full moon passes through all or part of Earth's shadow. The shadow cast by the Earth is composed of two parts. The inner-part, or umbra, is the region where no sunlight gets through. The outer-part, or penumbra, is a region that only partly blocks the sun. When themoon is in the umbra it's completely dark, but if its in the penumbra, it's only shadowed.

There is a full moon every month (when the sun, the Earth, and the moon line up in that order), but most of the time the moon passes above or below Earth's shadow. Lunar eclipses, therefore, only happen two to four times a year when the moon moves through some part or all of Earth's shadow.

During a total lunar eclipse, the entire moon passes through Earth's umbral shadow. In a penumbral lunar eclipse, like the one occurring tonight, the moon passes through Earth's penumbral shadow, which isn't as dark. Penumbral eclipses are typically very subtle, and usually go undetected by observers.

The eclipse begins at 5:50 p.m. EDT, but the shading won't be visible until around 7:30 p.m. EDT, when at least two-thirds of the moon's disk is in the penumbral shadow. The most noticeable phase of the eclipse occurs at 7:50 p.m. EDT. The viewing period of the eclipse will end around nominal eclipse visibility from about 23:30 to 00:10 UT.

You can also watch the eclipse live online, which will be broadcast by the Slooh Space Camera.