A lunar eclipse occurs when the moon passes directly behind the Earth into its umbra (shadow). This can occur only when the sun, Earth, and moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a full moon.
What is a lunar eclipse?
When a full moon passes directly behind Earth and into its shadow, it produces a lunar eclipse. The moon does not disappear completely during an eclipse, however; it remains illuminated by sunlight that passes through Earth’s atmosphere onto its surface. This indirect illumination is red in color, producing what is commonly referred to as a blood moon. Although somewhat rare, lunar eclipses can occur multiple times in a given year or even within just a few months of each other.
How did we get there?
The moon gets its reddish tint from what astronomers call Rayleigh scattering, which occurs when light passes through Earth’s atmosphere. This can also happen with light coming from other sources, like sunlight reflected off Saturn’s moon Titan. The red color in a lunar eclipse comes from light passing through our atmosphere being bent towards Earth—just as an observer standing on Mars would see an Earth eclipsed moon appear red.
How long will it last?
The eclipse will take approximately one hour and 43 minutes. It will start at 8:25pm ET, peak at 9:29pm ET, and end at 10:07pm ET. According to NASA’s broadcast of a total lunar eclipse, this should be long enough for skywatchers on Earth to witness the entire process from beginning to end. The moon will remain in a reddish glow until it slips out of Earth’s shadow again around 11:41 p.m.
What will it look like?
Don’t worry, you don’t have to be a NASA astronaut to get a good view of tonight’s lunar eclipse. In fact, all you need is your local news channel—and a friend to watch it with. During tonight’s blood moon, millions of people in North America will be able to see up to three hours of totality when our planet passes between Earth and sun and blocks out all sunlight from our closest neighbor.
Where can I see it?
The best views of a lunar eclipse happen when you’re not looking through Earth’s atmosphere. Astronauts aboard the International Space Station will have a front-row seat. The event can also be observed from Australia, Asia, Africa, Europe, South America and other parts of North America (weather permitting).
Why should you care?
During a lunar eclipse, people use special glasses that allow them to safely look at a blood moon in all its cosmic glory. Our celestial neighbor appears rusty red because sunlight is being refracted through Earth’s atmosphere, but how does a blood moon influence us on Earth? According to astrologists, lunar eclipses have far-reaching impacts on human life.