With Monday’s total solar eclipse rapidly approaching, Americans are running out of time to prepare for the much-hyped event—the first time since 1979 that people in the continental U.S. will be able to see the moon completely block out the sun.

As you’ve no doubt heard, you can’t watch this astronomical anomaly with the naked eye, or even with good sunglasses. The sun’s rays are too intense for your retina to handle, and looking directly at even the partially-obscured sun can cause permanent damage to your eyesight.

The only time it’s safe to look directly at the eclipse is during the 1 or 2 minutes that the moon completely blocks the sun, and only people watching from a narrow band from Oregon to South Carolina—known as the path of totality—will witness that. At all other moments, and for all those watching the partial eclipse from elsewhere in the U.S., you’ll need to protect your eyes.

Unfortunately, the certified sun-safe eclipse glasses available to order online are going quickly. Many approved and reputable online vendors are already sold out.

“No one expected there to be such a big demand,” says Mike Kentrianakis, the solar eclipse project manager for the American Astronomical Society.

If you haven’t gotten yours yet, here are a few options. Just be sure that both the vendor and the glasses’ manufacturer are included on the American Astronomical Society’s list of approved glasses sellers and makers, which you can find here.

If You’re Looking to Buy . . .

Online vendors, from scientific equipment suppliers such as Flinn Scientific to trendy eyewear outlets such as Warby Parker, have been offering certified eclipse glasses for purchase or even free. At this point, though, supplies are probably running low, or completely gone.

You can try stopping by your local Warby Parker to see if it still has any available, but the company won’t be able to share store-specific availability over the phone.

MORE ON the Eclipse

If you want to test your luck ordering online, beware of buying from just anywhere. Some sites are selling counterfeit eclipse glasses that may not protect your eyes. Also keep in mind that at this point, overnight shipping is the only chance of getting to you in time—and even that’s a gamble.

If You Can Attend An Event . . .

Many science centers are hosting eclipse viewing events and will provide special eclipse glasses on a first-come, first-served basis on the day of the eclipse.

“See what the local science museum has planned,” suggests Todd Happer, a spokesman for the Association of American Science-Technology Centers. “They live and breathe making science possible and accessible to people.” You can click here to search for a science center near you.

Libraries are another good bet—many are hosting eclipse events and may have large supplies of glasses available for participants, according to Kentrianakis. The National Aeronautics and Space Administration has compiled a map of participating libraries—you may be able to get glasses at one.

If you’re attending an event without your own glasses, though, plan to arrive early or make friends with someone who has some. Supplies are limited.

If You Can’t Get Glasses…

Your eclipse isn’t ruined. You can easily create a pinhole camera, a simple device that passes light through a small hole and projects an image of the sun onto a surface.

Here’s how—with materials you probably already have at home:

  • Take two sheets of stiff white cardstock and cut a square hole in the middle of one of them.

  • Tape aluminum foil over the hole.

  • Use a pin or paper clip to poke a hole in the foil.

  • Place your second piece of cardstock on the ground and hold the piece with the foil above it with the foil facing up.

  • Stand with the sun behind you and view the projected image on the cardstock below.

  • Adjust until you can see a small circle of light, projected from the pinhole, on the other sheet of paper. That’s a tiny image of the sun, which will become crescent-shaped as the moon moves across it.

“No need to buy anything,” Kentrianakis says. “It’s just as fun and comfortable. And it’s free.”

For a slightly more advanced version, try making a pinhole camera out of a cereal box. You can use NASA’s guide here.

If You Can't Go Outside . . .

Stuck at your desk? Unwilling to settle for a partial solar eclipse and too late to travel to the path of totality? NASA has you covered.

You can livestream the eclipse as it happens, starting at 1 p.m. Eastern Daylight Time. NASA’s livestream will include views of the eclipse from satellites, high-altitude balloons, and telescopes. 

If You Oversleep . . .

Not to worry. The next total solar eclipse visible in the continental U.S. will be in 2024. It will chart a path from Texas all the way up through Maine.