By Dan Klepal
The Cincinnati Enquirer

INFOGRAPHIC

• How a lunar eclipse works

A total lunar eclipse will make the moon look like a penny in heaven to most people in the Tristate tonight, if clouds don't get in the way.

The first eclipse of the year will become visible at 10:03 p.m. and continue until 1:17 a.m. Friday.

Lunar eclipses can happen only at full moon, and only when the moon passes through some portion of Earth's shadow, which is composed of two cone-shaped parts - the penumbra, an area where Earth blocks only a portion of the sun's rays; and the umbra, the inner portion where all direct sunlight is blocked.

It's impossible to predict exactly how the eclipse will look because the moon's exact color and brightness depend on the amount of dust in the Earth's atmosphere. But it will appear reddish because the only sunlight illuminating it will be from the red spectrum, like a sunrise or sunset.

"The red portion of sunlight is bent and passes through our atmosphere and gets into the dark shadow of Earth," said Paul Nohr, an astronomer at the Cincinnati Observatory.

The next total lunar eclipse will be in November, and it also will be visible in the Tristate.

E-mail dklepal@enquirer.com