Fewer than 136 days remain until the largest total solar eclipse the U.S. has seen in nearly 100 years.

UT Professor Mark Littmann, Hill Chair of Excellence in Science Writing, encourages everybody to make plans to see it.

It's not that total eclipses themselves are rare - one happens about every year and a half - it's an eclipse of this magnitude in the U.S. that's special.

"The last time an eclipse of the sun - a total eclipse of the sun - went all the way across the country, from the west coast to the east coast, was 1918," Littmann said.

He would know: he's written a book on the subject, called "Totality: The Great American Eclipses of 2017 and 2024."

He shared his knowledge at UT's weekly Friday Science Forum.

"It's such a wonderful and surprising sight, to have the moon completely cover the sun," he said. "You see parts of the sun that you can never see otherwise."

The celestial event will darken a band across the U.S., which cuts through East Tennessee, for up to approximately 2.5 minutes on the afternoon of Aug. 21.

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There's one part you'll especially want to see with your own eyes, Littmann said.

"Above all, you see the corona, this white-ish, filamentary gauze that extends outward from the sun in all directions," he said.

In terms of viewing, Littmann advised, use eye protection while the moon is in the process of covering the sun, but once the eclipse is total, he said, you're safe to look at it directly.

"Very, very few Americans, unless they've been willing to travel the world, have seen total eclipses," Littmann said.

That because while total eclipses happen regularly, they often fall over the ocean or in sparsely populated places like Antarctica.

You don't need a telescope to see the eclipse, he said, but you can bring binoculars, as long as you use them only during the total eclipse.