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In the early hours of Tuesday, darkness will slide across the moon’s surface before it turns a deep blood red. No, it’s not a harbinger of Election Day — it’s one of the most dramatic sights in the night sky.
In the U.S., anyone awake will sit in the front row, as the Sun, Earth and Moon line up, causing the Moon to pass through Earth’s shadow in the last total lunar eclipse before 2025.
“For me, the most important thing about a lunar eclipse is that it gives you a sense of three-dimensional geometry that you rarely see in space — the shadow of one sphere passing through another,” said the institute’s chief scientist, Bruce S. Bruce Betts said. Planetary Society.
Here’s what you need to know about viewing a solar eclipse.
When and where to watch a solar eclipse
In North America, West Coast observers will have the best views. At 12:02 a.m. PT, the moon will enter the outer part of Earth’s shadow and become so faint. But the full phase of the total solar eclipse — the real star — doesn’t begin until 2:16 a.m. That phase is known as a total eclipse, when the moon enters the darkest part of Earth’s shadow and glows a deep blood-red hue. Totality will last about 90 minutes until 3:41am, and at 5:56am, the moon will return to its proverbial silvery hue.
“The big problem here is before Election Day,” said Andrew Flacknoy, an astronomer at the University of San Francisco. “I joke that a lot of people are so nervous about Election Day this year that they might stay up all night, and They can watch.”
East Coast viewers, on the other hand, will have to set the alarm early. While they won’t be able to watch the entire eclipse, they can catch it, which runs from 5:16 a.m. to 6:41 a.m. ET, around the time the moon sets in the far northeastern United States. Early risers should look toward the northwest horizon to catch the Ruby Moon.
For those in the Midwest, from 4:16 a.m. to 5:41 a.m. Central Time, a total eclipse will dye the moon red. For those in the Rockies, totality happens an hour earlier.
Forecasters are predicting rain on the West Coast overnight, which could affect eclipse observations. From Minneapolis to cities in Texas, some cloudy skies or fog could be expected in the central US. Weather reports show mostly sunny weather on the east coast overnight.
Outside of North and Central America, skywatchers will be able to observe the eclipse in East Asia and Australia, which will take place in the evening after moonrise. NASA’s visibility map provides more details.
No matter where you are and what phase of the eclipse occurs, it is safe to observe with the naked eye.
What makes a blood moon?
Surprisingly, when the moon enters Earth’s shadow, it doesn’t simply dim. That’s because moonlight is usually just reflected sunlight. While most of the sunlight is blocked during the lunar eclipse, some of it orbits the edges of our planet — the verge of sunrise and sunset at the time. This filters out shorter, bluer wavelengths, allowing only redder, longer wavelengths to hit the moon.
“The romantic way to look at it is that it’s kind of like seeing all the sunsets and sunrises on Earth at once,” said Dr. Bates said.
This view is very different from that of some of our ancestors. “For many cultures, the disappearance of the moon is seen as a dangerous, chaotic time,” said astronomer Shanil Villani of George Washington University.
For example, the Incas believed that jaguars attacked the moon during a solar eclipse. The Mesopotamians saw this as an attack on their king. In ancient Hindu mythology, a demon swallowed the moon.
But not all lunar eclipses produce the deep red color that has led to the “blood moon” moniker. Just as the intensity of a sunrise or sunset changes from day to day, so does the color of a solar eclipse. It relies primarily on particles in our planet’s atmosphere. Wildfire smoke or volcanic dust can deepen the red hue of a sunset, as well as affect the hue of a lunar eclipse. But if the atmosphere is particularly clear during the eclipse, more light will pass through, resulting in a lighter red moon, possibly even a reddish-orange moon.
Using solar eclipses to study exoplanets
Thus, the moon’s color can reveal the signature of our own atmosphere — a trick that could be used for future observations of planets around distant stars.
Astronomers don’t usually observe exoplanets directly. Instead, they look for transits, or signal points of light when a planet passes in front of its parent star. During this time, starlight is filtered through the exoplanet’s atmosphere, just as sunlight passes through Earth’s atmosphere before hitting the moon during a lunar eclipse.
This means that astronomers can view a lunar eclipse as a proxy for the transit of an exoplanet. “It basically uses the moon as a mirror to watch Earth pass the sun,” said astronomer Alison Youngblood of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
January 2019, Ph.D. Youngblood and her colleagues trained the Hubble Space Telescope on the Moon during a total lunar eclipse. Because chemicals in Earth’s atmosphere are supposed to prevent certain wavelengths of sunlight from reaching the Moon — thereby leaving a dip in the observed spectrum — Dr. Youngblood’s team was able to detect ozone.
“It’s kind of like a practice round,” says Dr. Youngblood said. By treating Earth as an exoplanet, astronomers can double-check that they’re detecting atmospheric details correctly when looking at other stars.
But University of Arizona astronomer Manisha Shrestha has another idea. She plans to observe the lunar eclipse on Tuesday at the Bock telescope at Kitt Peak National Observatory in Arizona, hoping to spot not only certain chemicals in our atmosphere, but their distribution.
The technique has never been performed on exoplanets before, which could mean that future detections won’t simply reveal whether exoplanets have clouds, but whether those clouds will be as thick as those on Earth. Layers cover the world, or if they are slightly uneven. If these clouds are both inhomogeneous and composed of water vapor, that exoplanet could be Earth 2.0.
But you don’t need a scientific reason to enjoy a solar eclipse. Astronomers agree that this is a perfect opportunity to take a break from the politics of election season and simply think about the universe.
“From a cosmic perspective, our problems are temporary — those things that are delivering human fantasies,” said Dr. Flacknoy said. “Solar eclipses connect you to older cycles and rhythms.”