A partial lunar eclipse is expected to be visible before dawn on Friday, Nov. 19. The moon will look red as Earth’s shadow covers the full moon. But since it’s a partial lunar eclipse, a bright white sliver of the moon will still be visible.

What is a lunar eclipse?

A lunar eclipse happens when Earth gets in the way of the light from the sun hitting the moon. The moon looks red during a lunar eclipse because of the Earth’s atmosphere, which scatters blue light and only allows red to pass through.

Lunar eclipses occur about twice a year.

What time should I go out and look?

Edward Murphy, anastronomy professor at the University of Virginia, recommends going out at 2:15 a.m. ET to see the Earth’s shadow start to creep into the full moon. He also recommends going back out at 4 a.m., when the shadow will almost cover the entire moon and be dark red.

The website timeanddate.com is a reference to help find when the lunar eclipse will start or end in your area, and what it will look like at certain times, said Shannon Schmoll, director of the Abrams Planetarium at Michigan State University.

What parts of the U.S. will have the best views?

Most of the U.S. will have a pretty good view of the lunar eclipse, Ms. Schmoll said. It will also be visible from Northern Europe, East Asia and Australia, she said.

Do I need special equipment to see it?

No. Unlike solar eclipses, lunar eclipses are safe to view with the naked eye. “Just go outside and look up at the moon,” Ms. Schmoll said.

Why is it called the Beaver Moon?

It’s a nickname. The Maine Farmers’ Almanac started publishing Native American names for full moons in the 1930s, according to the National Aeronautics and Space Administration. The November full moon was called the Beaver Moon because it was either when beaver traps were set or when beavers were preparing for winter. Other nicknames for the full moon in November include the Frosty Moon and the Snow Moon, according to NASA.

Is there something special about this partial lunar eclipse?

Fred Espenak, a retired NASA astrophysicist and author of “Five Millennium Catalog of Lunar Eclipses,” said this is expected to be the longest partial lunar eclipse since Feb. 18, 1440, or 581 years ago.

It’s expected to last 3 hours and 28 minutes.

Is there anything else to know?

The ancient Greeks discovered the Earth was round by seeing the planet’s round shadow on the moon, Mr. Murphy said. Eclipses also helped the Greeks calculate Earth’s size, he said.