What's a total solar eclipse and why this one is so unusual

August 5, 2017 by Marcia Dunn
In this Wednesday, Aug. 2, 2017 file photo, Emmalyn Johnson, 3, tries on her free pair of eclipse glasses at Mauney Memorial Library in Kings Mountain, N.C. Glasses are being given away at the library for free while supplies last ahead of the big event on Aug. 21. (Brittany Randolph/The Star via AP)

Total solar eclipses occur every year or two or three, often in the middle of nowhere like the South Pacific or Antarctic. What makes the Aug. 21 eclipse so special is that it will cut diagonally across the entire United States.

The path of totality—where day briefly becomes night—will pass over Oregon, continuing through the heartland all the way to Charleston, South Carolina. Those on the outskirts—well into Canada, Central America and even the top of South America—will be treated to a .

The last time a total solar eclipse swept the whole width of the U.S. was in 1918.

No tickets are required for this Monday show, just special eclipse glasses so you don't ruin your eyes.

Some eclipse tidbits :

WHAT'S A TOTAL SOLAR ECLIPSE?

When the moon passes between Earth and the sun, and scores a bull's-eye by completely blotting out the sunlight, that's a total solar eclipse . The moon casts a shadow on our planet. Dead center is where sky gazers get the full treatment. In this case, the will last up to 2 minutes and 40-plus seconds in places. A partial eclipse will be visible along the periphery. Clouds could always spoil the view, so eclipse watchers need to be ready to split for somewhere with clear skies, if necessary.

WHAT'S THE PATH ON AUG. 21?

The path of totality will begin near Lincoln City, Oregon, as the lunar shadow makes its way into the U.S. This path will be 60 to 70 miles wide (97 to 113 kilometers); the closer to the center, the longer the darkness. Totality will cross from Oregon into Idaho, Wyoming, Nebraska, Kansas, Missouri, Illinois, Kentucky, Tennessee, Georgia, North Carolina and, finally, South Carolina. It will also pass over tiny slivers of Montana and Iowa. The eclipse will last longest near Carbondale, Illinois: two minutes and 44 seconds. The biggest cities in the path include Nashville; Columbia and Charleston, South Carolina; Salem, Oregon; Casper, Wyoming; and just partially within, St. Louis and Kansas City, Missouri.

LAST TOTAL SOLAR ECLIPSES IN U.S.?

Hawaii experienced a total solar eclipse in 1991. But the U.S. mainland hasn't seen a total solar eclipse since 1979, when it swooped across Oregon, Washington state, Idaho, Montana and North Dakota, then into Canada. Before that, in 1970, a total solar eclipse skirted the Atlantic coastline from Florida to Virginia. Totality—or total darkness—exceeded three minutes in 1970, longer than the one coming up. The country's last total solar eclipse stretching from coast to coast, on June 8, 1918 , came in over Oregon and Washington, and made a beeline for Florida.

WHEN'S THE NEXT ONE?

If you miss the Aug. 21 eclipse—or get bitten by the eclipse bug—you'll have to wait seven years to see another one in the continental U.S. The very next total solar eclipse will be in 2019 , but you'll have to be below the equator for a glimpse. We're talking the South Pacific, and Chile and Argentina. It's pretty much the same in 2020. For the U.S., the next will occur on April 8, 2024 . The line of totality will cross from Texas, up through the Midwest, almost directly over Indianapolis, Cleveland and Buffalo, New York, up over New England and out over Maine and New Brunswick, Canada.

Explore further: Total solar eclipse 1st in 99 years to sweep width of US

Related Stories

Recommended for you

Researchers investigate the peculiar radio source IC 1531

October 17, 2018

An international team of researchers has investigated a peculiar extragalactic radio source known as IC 1531. The new study analyzes the nature of IC 1531's high-energy emission, suggesting that the source is a radio galaxy. ...

Astronomers find a cosmic Titan in the early universe

October 17, 2018

An international team of astronomers has discovered a titanic structure in the early Universe, just two billion years after the Big Bang. This galaxy proto-supercluster, nicknamed Hyperion, is the largest and most massive ...

Magnetic fields may be the key to black hole activity

October 17, 2018

Collimated jets provide astronomers with some of the most powerful evidence that a supermassive black hole lurks in the heart of most galaxies. Some of these black holes appear to be active, gobbling up material from their ...

Double dust ring test could spot migrating planets

October 17, 2018

New research by a team led by an astrophysicist at the University of Warwick has a way of finally telling whether newly forming planets are migrating within the disc of dust and gas that typically surrounds stars or whether ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

EmceeSquared
not rated yet Aug 05, 2017
Only people along the Totality Line will see a total eclipse. But people to the sides can see a partial eclipse, which is still pretty cool even if the whole landscape doesn't go dark.

How far to the side (degrees, miles) of the Line can even a partial eclipse be seen? Not just the Moon cruising unusually close to the Sun, but actually covering it.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.