The Moon will pass through Earth’s shadow March 13/14. Here’s how and when to watch.
This sequence of photos was taken during the Sept. 27, 2015 total lunar eclipse. Note that the top of the eclipsed Moon is darker, indicating that it was closer to the center of Earth’s umbra. Credit: Philippe Moussette
Another great celestial event is coming. And this one’s really easy to observe because you can see it with just your eyes. Not only that, but anyone in the U.S. under a clear sky will be able to watch it.
On Thursday, March 13 (and continuing into the 14th), the Moon will pass through the darkest part of our planet’s shadow, creating a total lunar eclipse. These events occur when the Sun, Earth, and the Moon line up in that order. Such events are unusual, but not rare. On average, total lunar eclipses happen every 2½ years.
What causes a lunar eclipse?
But you might note that the Sun, Earth, and the Moon line up monthly when there’s a Full Moon. So, why don’t we see an eclipse every month? The reason is that the Moon’s orbit is slightly tilted (about 5°) to Earth’s orbit around the Sun. So, for most “lineups,” the Moon is either above or below Earth’s shadow.
What to watch for during the eclipse
Each total lunar eclipse has seven main times of interest. Six happen when the penumbral, partial, and total phases begin and end, and the seventh is the moment of mid-totality.
Let’s break these terms down. Earth’s shadow has two parts: an outer lighter section called the penumbra, and a darker inner section called the umbra. The eclipse begins when Earth’s penumbra touches the Moon. Because the penumbra isn’t dark, it’s tough to observe this until some 30 minutes have gone by.
The partial phase starts when Earth’s umbra first touches the lunar surface. Now there’s a real contrast between the dark shadow and the bright lunar surface. It’s easy to watch the umbra slowly creep across the Moon’s face.
Totality begins when Earth’s umbra completely covers the Moon. This is the part that most people remember because the Moon doesn’t disappear. Rather, Earth’s atmosphere scatters some sunlight onto the darkened lunar surface. And depending on how much “stuff” (dust, ash, etc.) is in our atmosphere at the time, the Moon can appear light or dark orange, light or dark red (sometimes called a Blood Moon), or various shades of brown.
Related: Why can we still see the Moon’s disk during a total lunar eclipse?
When to watch this month’s lunar eclipse
Here are the times for this eclipse’s seven events:
Penumbral phase begins (the eclipse starts): 11:57:28 p.m. EDT, March 13
Partial phase begins: 1:09:40 a.m. EDT, March 14
Totality begins: 2:26:06 a.m. EDT
Mid-eclipse: 2:58:43 a.m. EDT
Totality ends: 3:31:26 a.m. EDT
Partial phase ends: 4:47:52 a.m. EDT
Penumbral phase ends (the eclipse is over): 6:00:09 a.m. EDT
Lunar eclipses are what I like to classify as easy observing. The only potentially hard part of this one is that totality may happen in the early-morning hours where you are. But you don’t have to watch the whole event. Set your alarm to go off about 15 minutes before totality. From then until the total phase begins, you’ll see the most dramatic color changes.
The next total lunar eclipse visible in the U.S. will happen Sept. 7. Unfortunately, it will be visible only in Hawaii and parts of Alaska. The next one visible across the U.S. will occur March 3, 2026.
Here’s wishing us all clear skies. Good luck!
