Parts of the US will get to see a total solar eclipse on August 21.
While the entire country will get to witness at least a partial eclipse, the lucky people who live along a 70-mile-wide streak will be able to see totality – when the moon crosses between the Earth and the sun, completely blocking out the sun’s light.
The eclipse kicks off with what’s called first contact, when the moon starts to pass across the sun.
- Getty Images
The moon will continue to cover up the sun, forming what’s known as a “crescent sun,” that looks like this.
After about an hour or so, the moon will almost completely block out the sun. At that point, you’ll start to see a bright light radiate out of the sliver of distance between the sun and the moon, known as the “diamond ring.”
A few seconds before totality begins, you can start to see an effect called “Baily’s beads”, in which the sunlight passes through the valleys on the surface of the moon. It lasts for only a few moments before the totality begins.
- Credit: Arne Danielson
Totality begins when the moon makes its second contact with the sun and entirely blocks it out. The view is about as bright as a full moon, and it’s safe to look without your solar filter glasses. (But that’s only true during totality.)
- Beawiharta Beawiharta/Reuters
During the total eclipse, you can see the corona — the sun’s outer atmosphere — surrounding the moon. Mark Littman and Fred Espenek, authors of “Totality: The Great American Eclipses of 2017 and 2024” recommend looking to see whether the corona looks symmetrical, or if it bunches up around the poles of the sun.
- M. Druckmüller/NASA
During this eclipse, totality will last a maximum of 2 minutes and 43 seconds. After that, the moon will continue on its way, making its third contact of the eclipse. Once again, you’ll briefly see Baily’s beads though (your solar filters should go on again).
- Robert Slobins
According to NASA, the longest possible total solar eclipse will occur on July 16, 2186. That will last 7 minutes and 30 seconds, and pass through Colombia, Venezuela and Guyana.
The light will start to intensify, creating another “diamond ring.”
- Dave Mosher
You’ll then start to see the crescent sun of a partial eclipse once again.
Soon after, the experience will be complete. At the fourth contact, the moon will cease to cover up the sun.
- Rick Fienberg / TravelQuest International / Wilderness Travel
As a reminder, the only time you can take your glasses off while looking at the eclipse is the few minutes of totality. If you’re still trying to find a pair of glasses, here’s where you might still be able to snag some for free. Those trying to take photos of the eclipse’s stages should be careful with their cameras, too.