On August 21st the moon will be pass between earth and the sun. The moon will cover at least part of the sun for 2 to 3 hours. Halfway through, anyone within a narrow path from Oregon to South Carolina (the 70 mile wide path of totality), will experience a brief total eclipse. The moon will completely block the sun for up to 2 minutes 40 seconds. In Boulder, people will witness a partial eclipse starting at 10.23am. At 11.46am, the sun will be 93% covered by the moon.
Science writer David Baron has been planning his latest book book American Eclipse for 19 years since he saw his first total solar eclipse. He says the 2017 eclipse is the first one in 99 years to cross the US from coast to coast. “A total solar eclipse is extraordinarily rare for any given point on earth.” The next total eclipse to cross Boulder will be in 700 years in the year 2772.
Baron cautions people to make sure they use appropriate safety glasses if they are planning on looking at the eclipse. Staring at even a partially exposed sun with the naked eye can cause significant damage. “That shouldn’t scare people away from enjoying the eclipse. If you have safe eclipse glasses you should look at it, and if you can get yourself to the path of totality for the 2 1/2 minutes when it is a total eclipse, you actually can look at the sun with a naked eye, that is the only time that it is safe.”
“One way to tell if your glasses are definitely not safe is if you hold them up to your eyes and try to look around the house, or look at a light bulb a few feet away…if you can see anything then they are unsafe. The only thing you should see through eclipse glasses frankly is the sun.”
American Astronomical Society Eclipse page has information about eye safety and a list of approved vendors for eclipse viewing glasses.