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Great American Eclipse underway

Posted at 11:59 PM, Aug 20, 2017
and last updated 2017-08-21 00:00:44-04

Folks have been waiting a long time for this! Solar eclipse day across the United States!

Other countries will be able to see a partial eclipse, but only the U.S. will experience totality. Totality is when our moon completely covers the sun. West Michigan will experience only about 80 percent totality and I expect a veil of high clouds through most of the day…a milky or obscured sun is likely what we’ll see with the eclipse still visible. The cloud cover may be a bit thinner across our southern counties. Local times for the eclipse are at the end of this story.

For the 14 states lucky enough to be in totality, or those of us heading further south around Carbondale, Illinois, you can expect the following under good sky conditions (no clouds):

About 10 to 15 seconds before and after complete totality, the corona or outer atmosphere of the sun becomes visible. It produces a diamond ring effect. See below.

Just seconds before and after totality Baily’s Beads appear. Those are bead-like pieces or blobs of light at the edge of the moon and are created because of gaps in the mountains and valleys on the moon’s surface. It allows the sunlight to pass through in those areas, but not others. See image below.

It really will be a true celestial spectacle complete with Baily’s Bead’s, the Diamond Ring, the sun’s corona, and the ability to actually see stars during the day as the sun is completely and momentarily blocked out. In fact, temperatures may fall as much as 20 to 25 degrees during totality as solar insolation is all but stopped! Remember that these things are only visible in 100 percent or full totality areas.

Since totality begins in the Pacific Northwest, the moon’s shadow (or umbra) will move eastward across the United States at more than 1,000 miles per hour! A total solar eclipse across the entire U.S. (like this) is rare. The last one occurred in 1918. We had one that was visible only in Hawaii in 1991, and another in 1979 visible only in the Pacific Northwest states. About 12 million people live in the path of totality, but millions more are expected to travel (even from other countries) to experience it. Only the United States will see totality (complete coverage of the sun). Other countries will only experience a partial eclipse. See image below.

Our moon is not the only thing to “eclipse” our sun. A transit of Venus occurred in June 2012 and a transit of Mercury occurred in May 2016. The transit means they come between Earth and the sun. Those are the only two planets that can ever transit the earth, but I should also note the effect is not nearly as dramatic as a solar or lunar eclipse.

For those of you into the astronomy portion of the eclipse, realize that a solar eclipse only happens at the new moon. That’s the only lunar phase when the moon is between the Earth and the sun. Eclipse totalities and the length of them will vary with the Earth-sun distance (that can change up to 3 percent) and the moon-Earth distance (that can change up to 12 percent). These variables can alter the actual totality time. Keep in mind that our daytime sun’s diameter is about 400 times larger than that of the moon. It also lies about 400 times farther away, so both disks appear to be the same size, hence the coverage/totality/eclipse of the sun.

Many believe this will be the most viewed eclipse ever due, to media coverage, the availability of a highway system that allows people to travel from various locations quickly and easily, and the fact that the eclipse will traverse 10 states across the nation’s midsection. Maximum totality is two minutes and 40 seconds around Carbondale, Illinois, or slightly south of there in Giant City State Park.

Here in West Michigan, the eclipse gets underway at the lakeshore at about 12:56 p.m. The 80 percent totality (maximum sun coverage for us) occurs about 2:21 p.m., and the event concludes about 3:43 p.m. at the lakeshore. Times are a minute or two later from Grand Rapids eastward since the eclipse travels from northwest to southeast.

Our next solar eclipse occurs on April 8, 2024. The path will be through Mexico, Texas, northwest Ohio, and Maine. The dark part of the eclipse or shadow is known as the umbra. The light part or partial eclipse (everyone that doesn’t experience totality) is known as the penumbra. See image below, courtesy of Michael Zeiler and TheGreatAmericanEclipse.com.

Make sure to enjoy this rare event and please be safe. Use only approved eclipse glasses to view the eclipse. And don’t forget to post any photos on our FOX 17 Facebook page. FOX 17 will be LIVE from 2:00 to 3:00 p.m. EDT on Monday streaming the event and getting reaction with crews in Carbondale, Illinois, and right here in West Michigan!