Yale Astronomer Explains January 20 Eclipse

The total lunar eclipse January 20 will cast the Moon in shadow for almost 78 minutes, says Yale Astronomy and Physics Professor Bradley Schaefer.

“No equipment is needed to observe the eclipse, although binoculars do improve the view,” said Schaefer. “The Moon will be entirely within the shadow of the Earth. This eclipsed Moon will be visible throughout North America from about 10:01 p.m. EST to 1:25 a.m. EST.”

A lunar eclipse is when the Moon moves, as part of its normal orbit around the Earth, through the shadow of the Earth cast by the Sun, he said. The shadow consists of an umbra, within which the Sun is totally blocked by the Earth, and a surrounding penumbra, within which the Earth only partially blocks the Sun.

“During the partial phases of the eclipse, the spherical shape of the Earth can be readily seen by the round shadow it casts onto the Moon,” Schaefer said. “During totality, when the Moon moves entirely within the umbra, it will appear faint and sunset-red.”

The Moon will appear in the constellation of Cancer, the Crab, in a direction almost exactly opposite the Sun, he said. The bright star Procyon will be visible to the southwest, the Gemini twin stars Castor and Pollux will be to the northwest, and the cluster of stars called the Beehive, or the Manger, will be visible directly east of the Moon. No planets will be visible, since they are all gathering near the Sun for the grand conjunctions in May, Schaefer said.

“It is best to watch the progress of the Moon through the shadow from the time it first touches the umbra through to totality and after,” Schaefer said. “Following the eclipse through the partial phases ensures that the Moon can be found during totality (between 11:05 p.m. and 12:22 a.m. EST).”