“Blood Moon” – What you need to know about the lunar eclipse

“Blood Moon” – What you need to know about the lunar eclipse

May 2022 lunar eclipse

The Moon moves from right to left, passing through the penumbra and umbra, leaving an eclipse chart showing the times at various stages of the eclipse. Photo credit: NASA Scientific Visualization Studio

What is a lunar eclipse?

A lunar eclipse occurs when the sun, earth, and moon align so that the moon casts the earth’s shadow. During a total lunar eclipse, the entire moon falls into the darkest part of the Earth’s shadow, the umbra. When the moon is in the umbra, it takes on a reddish hue. Lunar eclipses are sometimes called “blood moons” because of this phenomenon.

Earth's atmosphere scatters sunlight during the lunar eclipse

During a lunar eclipse, Earth’s atmosphere scatters sunlight. The sun’s blue light is scattered, and longer-wavelength red, orange, and yellow light is transmitted, coloring our moon red. *not to scale. Credit: NASA Goddard Space Flight Center/Scientific Visualization Studio

How can I watch the solar eclipse?

You don’t need any special equipment to view a lunar eclipse, although binoculars or a telescope will improve visibility and the red color. A dark environment away from bright light provides the best viewing conditions.

The eastern half of the United States and all of South America have the opportunity to see each phase of the lunar eclipse. Totality will be visible across much of Africa, Western Europe, Central and South America, and most of North America.

Total Lunar Eclipse May 2022 Visibility Map

A map showing where the lunar eclipse of May 15-16, 2022 will be visible. Contours mark the edge of the visibility range at eclipse contact times. The map is centered at 63°52’W, the sublunar longitude at the center of the eclipse. Credit: NASA Goddard Space Flight Center/Scientific Visualization Studio

What if it’s cloudy or I’m not in the viewing area?

What can I expect to watch?

UTC (May 16) EDT (May 15-16) PDT (May 15) milestone What’s happening?
1:32 9:32 p.m. May 15 — Moon not yet visible The penumbral eclipse begins The moon enters the penumbra of the earth, the outer part of the shadow. The moon begins to darken, but the effect is quite subtle.
2:27 10:27 p.m — Moon not yet visible Partial eclipse begins The moon begins to enter the umbra of the earth and the partial solar eclipse begins. As the moon moves into the umbra, it appears to the unaided eye as if a bite is being taken from the lunar disk. The part of the moon inside the umbra appears very dark.
3:29 11:29 p.m 8:29 p.m totality begins The entire moon is now in the umbra of the earth. The moon turns copper red. Try binoculars or a telescope for a better view. If you want to take a picture, use a camera on a tripod with exposure times of at least several seconds.
4:53 12:53 am May 16 9:53 p.m totality ends When the moon leaves the umbra of the earth, the red color fades. It will look like a bite is taken from the opposite side of the lunar disc like before.
5:55 1:55 p.m 10:55 p.m Partial eclipse ends The entire Moon is in Earth’s penumbra, but again, the darkening is subtle.
6:50 2:50 p.m 11:50 p.m The penumbral eclipse ends The solar eclipse is over.

What else can I see tonight?

The moon will be in the constellation Libra. Here are some more skywatching tips for the month of May.

Why does the moon turn red during a lunar eclipse?

The same phenomenon that makes our skies blue and our sunsets red causes the moon to turn red during a lunar eclipse. It’s called Rayleigh scattering. Light travels in waves, and different colors of light have different physical properties. Blue light has a shorter wavelength and is more easily scattered by particles in the Earth’s atmosphere than red light, which has a longer wavelength.

Red light, on the other hand, travels more directly through the atmosphere. When the sun is above us, we see blue light all over the sky. But when the sun goes down, the sunlight has to pass through more atmosphere and travel farther before it reaches our eyes. The sun’s blue light is scattered and longer-wavelength red, orange, and yellow light is transmitted.

During a lunar eclipse, the moon turns red because the only sunlight that reaches the moon goes through the earth’s atmosphere. The more dust or clouds in the Earth’s atmosphere during the eclipse, the redder the moon appears. It’s like all the sunrises and sunsets in the world are projected onto the moon.

Artist’s rendering of the Earth during a lunar eclipse from the surface of the moon. Seen from the moon, as in this animation, the earth hides the sun. A red ring, the sum of all sunrises and sunsets on earth, lines the edge of the earth and casts a reddish light on the lunar landscape. With the darkness of the eclipse, the stars come out. The lights of the cities of North and South America are visible on Earth’s night side. The part of the earth visible in this animation is the part where the lunar eclipse can be seen. Credit: NASA Goddard Space Flight Center/Scientific Visualization Studio

Will any NASA spacecraft observe the eclipse?

NASA’s mission team for the Lunar Reconnaissance Orbiter (LRO), NASA’s spacecraft in orbit around the moon, will turn off instruments during the eclipse. The spacecraft runs on solar power, so LRO shuts down to conserve battery power while the moon is in shadow.

The Lucy spacecraft, currently on its voyage for study purposes[{” attribute=””>Jupiter’s Trojan asteroids, will turn its gaze toward its home planet to observe a portion of the five-hour long eclipse – from just before the penumbral eclipse to just before the end of totality. The mission team plans to capture a view of both the Earth and the Moon with the high-resolution imager, L’LORRI. Since the spacecraft will be 64 million miles away and uses the Deep Space Network, it will likely take a few weeks to download and process the images.

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