Locals will see partial eclipse
August 17, 2017 · Erica Dawson
Eastern Iowa, including Mount Vernon and Lisbon, are in for a celestial spectacle during mid-day Monday, Aug. 21.
A solar eclipse, when the moon passes between the sun and Earth, casting a shadow on the Earth, will travel across the United States from coast to coast.
Mount Vernon and Lisbon will experience a partial eclipse, as the moon will only partially cover the sun. It will begin at 11:46 a.m. and end at 2:36 p.m., reaching its peak at 1:12 p.m.
"What we're going to see here in Eastern Iowa is about a 92- or 93-percent eclipse," said John Leeson, vice president of the Cedar Valley Amateur Astronomers and director of the Palisades-Dows Eastern Iowa Observatory. "Seven or eight percent of the sun will still be showing, which will look like the crescent moon."
In Eastern Iowa, "it's going to look a little bit dim, like a moderately cloudy day," he said. By comparison, the sky will still be 30,000 to 40,000 times brighter than the light from a full moon.
Leeson said if people can travel, "the best experience is to go to where the eclipse is total."
The eclipse will be total along a 70-mile-wide path across the central United States, through such cities as Grand Island, Neb., St. Louis, Mo., Kansas City, Kan., and Bowling Green, Ky.
"People say it's an amazing experience," said Kara Beauchamp, Cornell College professor of physics and astronomy. She is planning to travel south that day for her first total eclipse. She'll be going with friends and family for the experience as opposed to a scientific expedition.
"It's the best opportunity of my life," she said.
While it is safe to look directly at a total eclipse at its peak when the sun is completely covered by the moon, partial solar eclipses cannot be safely viewed with the naked eye without risking permanent eye damage.
"Never look directly at the sun," Leeson cautioned. "Any time you look directly at any portion of the sun, it's way, way, way too bright to look at with naked eyes."
The danger during an eclipse is that the shadow lessens people's natural aversion to the sun's brightness - squinting and looking away.
Leeson recommended instead looking at a projection or filtered image, or using a pair of eclipse glasses. The glasses cut out all but 0.001 percent of sunlight, which he said makes them much darker than dark glasses. Eclipse glasses are commonly available in stores right now, he said.
The American Astronomy Society has a list of recommended glasses.
Beauchamp said the light passing through any small hole will show the crescent caused by the eclipse - even the leaves on the trees. An easy way to project an image is by putting a pin prick in a piece of foil.
While there is a total eclipse somewhere in the world every two to three years, "they don't often hit in the United States," Leeson said. The last total eclipse in the lower 48 occurred nearly 40 years ago in the Pacific northwest. The last time the path of totality was entirely within the U.S. was in 1776.
The next total eclipse in the U.S. will occur on April 8, 2024, and will be an estimated 80 to 90 percent partial eclipse in Iowa, based on its path east of the state.
In places where the eclipse is total, it will look like dusk looking toward the horizons, and a halo, or corona, will be visible around the moon. The maximum duration of the total eclipse will be two minutes and 42 seconds.
"It will be dark enough that the birds think it's going to be night and they stop singing and go to bed," Leeson said.
The Eastern Iowa Observatory (located at 1365 Ivanhoe Rd. south of Mount Vernon) hosts a free public program Saturday, Aug. 19, from 3 to 6 p.m. As part of the "Solar Saturday" program, the group's president, Carl Bracken, will present about what causes eclipses and sunspot cycles.
Afterwards, participants will get the opportunity to use the telescopes. The program will also be offering eclipse glasses, which people will be able to take home with them.
Leeson said the observatory offers all kinds of special event coverage, ranging from this past week's Perseid meteor showers to super moon total eclipses.
The observatory will also be open during the eclipse Aug. 21. But anyone can experience the eclipse wherever they are.
"Go outside," Beauchamp said. "Go outside and look at the shadows."
The Eastern Iowa Observatory south of Mount Vernon hosts a free public program Saturday, Aug. 19, from 3 to 6 p.m. It will also be open Aug. 21 for the eclipse.