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Solar eclipse 2017: what you need to know

Aug 16, 2017

On Aug. 21, for the first time in nearly a century, an exciting earthly phenomenon will occur for nearly three minutes: a total solar eclipse visible from coast-to-coast. 

According to NASA, a solar eclipse takes place during the new moon, when the moon passes in front of the sun, completely blocking the sun’s radiant light. This causes a shadow to be cast on the Earth.

The path of the total eclipse, referred to as the path of totality, will sweep across the U.S. from the Oregon coast to the South Carolina coast between 10:17 a.m. and 2:47 p.m. While the entire country will be able to see the eclipse, it will not appear the same everywhere. As the Earth spins during the eclipse, certain sections of the U.S. will see different versions: a partial or a total shadow.

Infographic detailing solar eclipse details for each campus
An accessible version of this graphic is available online.Graphic by Milana Katic, IU Communications

And while Indiana isn’t in the path of totality, a partial shadow will be visible from all Indiana University campuses.

There are cities where the eclipse will be more visible than others. At 99 percent covered, Evansville is the best city in the state to view the eclipse. For cities with IU campuses, New Albany will be 95.7 percent covered; Bloomington, 93.9 percent; Columbus, 92 percent; Indianapolis, 91.5 percent; Richmond, 89.5 percent; Kokomo, 89.1 percent; Gary, 87.2 percent; and South Bend, 85.5 percent.

While partial or annular eclipses – where the Moon covers the Sun’s center, leaving a ring-like shape visible – occur more frequently, only 14 total solar eclipses have been visible in the United States over the past 100 years. This is the first total coast-to-coast solar eclipse since 1918 – before the interstate highway system even existed.

“Eclipses are rare events for two reasons: the size of the moon’s shadow, which is only about 70 miles wide, and the 5-degree tilt of the moon’s orbit, which causes it to rarely line up between the sun and the Earth,” said Patrick Motl, an associate professor of physics and associate dean in the School of Science at IU Kokomo.

According to Motl, a total solar eclipse only occurs on any given spot on Earth every 375 years.

Safe viewing

Looking directly into the sun can do serious damage to one’s eyesight, which is why it’s imperative to take the proper safety precautions before viewing the eclipse.

“The only safe way to view a partial solar eclipse is using special solar filters, such as ‘eclipse glasses’ or hand-held solar viewers,” said Arthur Bradley, an IU School of Optometry professor. “Looking at the sun without proper equipment will damage the fovea, the most important part of the retina. Often people aren’t even aware of the damage since the retina lacks pain receptors.”

To safely view the eclipse, Bradley recommends using a solar viewer from one of five manufacturers found to meet international eye safety standards by the American Astronomical Society or a pinhole projector.

Students looking up at the sky through solar eclipse glasses
Proper solar eclipse viewing glasses should be used to ensure safety while viewing the eclipse.Photo courtesy of the Office of Science Outreach

Celestial celebrations

Along with the distribution of proper solar eclipse viewing glasses, activities will take place on IU campuses across the state in honor of the rare phenomenon. See what your campus has planned:

The next solar eclipse visible in the United States will occur in 2024. For that eclipse, several IU campuses will be in the path of totality.

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