On Aug. 21, a total solar eclipse will occur over the United States for the first time in more than 20 years. The last time a total eclipse was visible across the entire Lower 48 was 1979, and the next time it happens is 2045, so the excitement level is high.

NASA is giving free party-planning advice. The Exploratorium in San Francisco and Slooh.com already have their live-streaming Eclipse 2017 sites set up. It’s going to be a huge deal. Notably, it also might be the day social media finally explodes.

“This will be the most photographed, the most shared, the most tweeted event in human history,” said one astronomer at a meeting of the American Association for the Advancement of Science.

Granted photography has only existed for about 200 years, so it’s a short history. But in general, we agree — the Internet won’t have bandwidth for anything other than the solar eclipse on Aug. 21.

It begins around 9 a.m. Pacific on the West Coast and will be seen over 11 states before it ends on the East Coast around 4 p.m. Eastern. From coast to coast, the event will last a little more than an hour, but only for 20 seconds to about 2 minutes in any given location along the path of totality.

(Fun to think about: If you were able to fly across the United States along the path in two hours, you would be able to see eclipse totality the entire time.)

There will be countless ways to see the eclipse online, and from any location in the Lower 48 you will be able to see at least a partial eclipse. You need to be in that highlighted path to see the moon cover the sun completely.

If you really want to see it in person, start planning now. Hotel rooms are almost totally booked along the path of totality and just outside that path. Flights into airports near the path are filling up, and I’m guessing they will get pretty expensive.

There are a few lucky major cities that just happen to be in the path where the sun will be 100 percent covered by the moon. Half of Kansas City and St. Louis, most of Nashville and all of Columbia and Charleston, S.C. It will be close enough to Portland, Ore., and Atlanta for people to drive to the path, but I can imagine people even farther away than that will make the day trip.

The experts at greatamericaneclipse.com suggest a few locations that are off the beaten path:

  • Madras, Ore.
  • Snake River Valley, Idaho
  • Casper, Wyo.
  • Sandhills of western Nebraska
  • St. Joseph, Mo.
  • Carbondale, Ill.
  • Hopkinsville, Ky.
  • Great Smoky Mountains National Park

One of those experts also created what I have found to be an incredibly useful eclipse resource — the path of totality on a Google Map. If you want to buy eye protection in advance (advisable) they also have gear ranging from eclipse shades to “sunoculars.”

Correction: Fixed some timing — the eclipse ends around 20 UTC or 4 p.m. on the East Coast.