COSMIC WATCH: Get ready for the solar eclipse on Monday

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Progression of a total solar eclipse as the moon glides across the sun. Central Wisconsin won’t see a total eclipse, but the 83% coverage will noticeably change the daylight.

The cosmic event of the year is coming Monday, Aug. 21—a total eclipse of the sun seen in some parts of the U.S., and a partial eclipse visible in Central Wisconsin. The last time the mainland U.S. experienced a total solar eclipse was Feb 26, 1979, visible only in a tiny corner of the Pacific Northwest. This time, viewers from coast to coast will experience seeing the moon cover at least most of the sun. In Wisconsin we’ll see a about 83% coverage.

The eclipse here begins at 11:50 am, with maximum coverage at 1:13 pm, and the event ending at 2:34 pm.

It’s an awe-inspiring natural event that people have described as overwhelming: There’s a “hole in the sky” where the sun should be; one can “feel” the workings of the solar system.

The most important thing to remember is this: Never look directly at the sun, even during an eclipse, as this will cause permanent eye damage. Sunglasses, even doubled up, are not adequate. It’s possible to view the eclipse safely with special eclipse glasses, but beware of scams—many online sellers are taking advantage of the hype and selling so-called eclipse glasses that are not safe.

You can watch the moon glide across the sun by making a simple pinhole projector. Poke a hole in a piece of cardboard and hold a sheet of paper beneath it; the image on the paper will be the eclipsed sun.

The eclipse also can be seen in the dappled light under a tree. The leaves create natural pinhole projectors, resulting in fascinating, crescent shadows.

How rare is this? For most people a solar eclipse this dramatic is a once in a lifetime event, though in an unusual confluence, there will be another total solar eclipse seen in the U.S. in 2024.

It’s not rare that the moon crosses the sun—this happens about two or three times a year. But only sometimes does the moon line up perfectly to totally eclipse the sun (13 times since 2001).

Location is what makes viewing an eclipse so rare. Only a small part of the world can see that two-hour event happen, and only a narrow swath will see total coverage. This is why Central Wisconsin will experience 83% coverage while southern Illinois will see 100%.

The Marathon County Public Library in Wausau is holding a Solar Eclipse Viewing Party Monday starting at 11 am. You can create pin-hole viewers, watch videos about the eclipse, then head outside to view the event. Free and supplies provided. In case on inclement weather, there will be live-feed video of the eclipse to watch.

What the eclipse will look like in Central Wisconsin: The sky won’t turn dramatically dark, as we won’t experience a total eclipse. According to NASA’s Eclipse 101, you might not even notice an illumination change until the sun is at least 75% covered. We’ll see 83% coverage maximum, so at this point—around 1:13 pm— the midday light will change. Outdoor shadows will become muted and you’ll see crescent-shaped shadows under trees.

Visit eclipse2017.nasa.gov for a complete guide to the solar eclipse. Happy safe viewing.