The Great American Eclipse is about 100 days away
This summer, darkness will fall across the face of America.
Birds will stop singing. Temperatures will drop.
Stars will become visible in the daytime sky.
In about 100 days, a total solar eclipse will sweep across the continental United States for the first time since 1918. Astronomers are calling it the Great American Eclipse.
For the amateur sky-watcher, a total eclipse presents a rare opportunity to witness a cosmic hiccup in our day-night cycle.
For solar astronomers, the eclipse offers something else: three minutes (give or take) to collect as much data as possible about the sun’s usually hidden outer atmosphere.
Researchers have been anticipating the event for years.
Some will take measurements from the sky; others have engaged vast networks of citizen scientists to track the eclipse as its shadow moves across the ground. Ultimately, they hope their findings will tell them more about the sun’s magnetic field, the temperature of its outer atmosphere and how energy moves through the star and out into space.
If you remember donning those paper eclipse glasses to watch as the moon appears to take a bite out of the sun, you may think you have seen a total eclipse. But you haven’t.
What you witnessed was a partial eclipse, a phenomenon as different from a total eclipse as day is from night. Literally.
The sun is so bright that even when 99 percent of it is covered by the moon, the remaining 1 percent is still bright enough to make the sky blue, said Jay Pasachoff, an astronomer at Williams College in Massachusetts who has seen 33 total eclipses and 32 partial eclipses. During a total solar eclipse, the moon completely obscures the face of the sun, causing the daytime sky to darken by a factor of 1 million.
This moment of totality lasts only a few minutes. Those who have seen it say it’s unlike anything they’ve ever experienced.
A total solar eclipse occurs somewhere on Earth about once every 18 months, and it can happen absolutely anywhere. That means most eclipse-chasers have to travel far from home to see one for themselves.
On Aug. 21, however, what’s known as the path of totality will cut a 60-mile-wide arc across the United States, beginning in Oregon at 10:15 a.m. local time and ending in South Carolina about an hour and a half later.
Experts estimate 11 million people won’t have to travel at all to observe the total eclipse, and an estimated 76 million more will be within a 200-mile drive of it.
Because of this unusual accessibility, it will probably be the most-viewed eclipse of all time.