(Photography by Jean Lachat)

Nighttime at noon

UChicago astronomers and astrophysicists prepare for a total eclipse of the sun.

On August 21, 2017, everyone in North America and parts of South America, Africa, and Europe will see at least a partial solar eclipse, lasting two to three hours. If you’re within the path of totality, a 70-mile-wide ribbon that stretches through 14 states from Oregon to South Carolina, you will see a total eclipse of the sun.

The sun’s corona during a total solar eclipse, captured during a Williams College eclipse expedition in Lusaka, Zambia. (Photo courtesy NASA)

Astronomy buffs have long been preparing for this eclipse—renting hotel rooms and reserving campsites all along the path of totality, sometimes years in advance. Among those eclipse chasers are several members of the UChicago Department of Astronomy and Astrophysics faculty. William E. Wrather Distinguished Service Professor Robert Rosner will be camping with his family in eastern Oregon. “This will be the second total solar eclipse for my wife, my two daughters, and me,” he says, “but for others—including our two grandchildren—this will be a first.”

Physical Sciences Division dean Edward “Rocky” Kolb will travel to Jackson, Wyoming, with his family to watch the eclipse. Associate professor Daniel Holz plans to “head to St. Louis, drive south from there, and hope to find an open field with clear skies above.” This will be his first total solar eclipse. And associate professor Daniel Fabrycky will drive to Tennessee with his family. “I really look forward to seeing the solar corona with my own eyes,” he says, “and making a memory for my children.”

So why are these astronomers, and millions of other eclipse enthusiasts, so excited? You might be thinking, didn’t I see a solar eclipse, like, yesterday? Well, odds are—if you live in the United States—you saw a partial or annular eclipse. Annular eclipses occur when the moon is near its farthest point from Earth, so it appears smaller to us and doesn’t block the entire sun, leaving a “ring of fire,” which admittedly is still cool. During a true total eclipse—not seen in North America since 1979—the moon is near its closest point from Earth, and the corona, the sun’s normally hidden outer atmosphere, appears as an incredible light show.

This is what an annular eclipse looks like from Mars as one of its moons, Phobos, passed in front of the sun. NASA’s Mars rover, Curiosity, took these shots three seconds apart. (Photo courtesy NASA)

The eclipse isn’t just neat to look at—scientists use the opportunity to study interactions between the sun and Earth to improve understanding of how the sun’s radiant energy in Earth’s atmosphere changes when clouds, particles, or the moon block sunlight. Eleven spacecraft, more than 50 NASA-funded high-altitude balloons, numerous ground-based observatories, and citizen scientists will capture images and data.

Will you be chasing the eclipse? Remember, you must wear protective filtered eyewear to look directly at the eclipse, and watch out for knock-offs. If you prefer to observe indirectly, you can make the classic pinhole projector most of us learned in grade school to shine an eclipse shadow on the ground. But anything with holes will work, even a cracker!

If you miss this year’s total solar eclipse, don’t worry. You get another chance in 2024. Book your travel now.