The sky will darken, temperatures will drop and animals will go quiet on the afternoon of Aug. 21 when a solar eclipse passes over the continental U.S.
A solar eclipse occurs when the moon passes between the earth and the sun, causing the moon to cast a shadow that will hit the earth, according to NASA research scientist Michael Kirk, who specializes in solar imaging.
The moment when the moon completely covers the sun is called "totality," and puts the sky in total darkness, Kirk said. When this occurs, temperatures drop between 10 and 15 degrees, and animals are known to go quiet out of confusion over the sudden darkness. At the moment of totality the sun's corona — an aura of plasma that surrounds the sun — is visible from behind the moon, something which is normally hidden from the human eye, according to Kirk.
Solar eclipses occur approximately every 18 months, but Kirk said it can take hundreds of years for an eclipse to occur again in the same spot, and often they occur in remote places or over the ocean. When the eclipse sweeps over the continental U.S., Kirk said it will likely be the most-viewed eclipse in the history of the world because of the number of people who can easily travel to a view of the phenomenon.
Marylanders won't get to view the full effect of the phenomenon as the state will only reach about 85 percent totality and the skies won't completely darken. But Kirk said it's still worth stepping outside for a few minutes in the afternoon to view the moon partially eclipse the sun.
The best time to view the eclipse in central Maryland will be between 1 and 3 p.m., according to Joel Goodman of the Howard Astronomical League. It will take approximately 90 minutes for the sun to become 85 percent covered, and another 90 minutes for it to be fully visible again, according to Goodman.
For those in Maryland who do step out to see the partial eclipse, Goodman said it is vital that they wear certified solar viewing glasses, which are more protective than average sunglasses, to protect them from the sun's harsh rays, which can cause permanent eye damage when looked at directly for too long. The county's Recreation and Parks Department sent an alert Tuesday that solar-eclipse glasses handed out at the department's July 8 Solar Fest have been recalled by Amazon, where they were purchased, because of safety issues. County officials said those glasses should not be worn to view Monday's solar eclipse as they might not provide adequate protection.
Goodman and several other members of the league are headed to different parts of the country to view the full eclipse, including Idaho, Nebraska and Kentucky. Goodman is headed to Wyoming where he'll be near the center line of the eclipse, giving him one of the best views of the phenomenon at almost 100 percent totality.
The group, which has an observatory at Alpha Ridge Park in Marriottsville, is not hosting any viewing parties for the eclipse since many members will be out of the state. The Benjamin Banneker Historical Park and Museum, in Catonsville, will host a viewing party from 1-3 p.m., and Howard County libraries will host viewing parties at the Glenwood and Savage branches from 1:30 to 3:30 p.m., and at the Miller branch from 2 to 3 p.m.
Fascination with solar eclipses dates back thousands of years. The first written account of a solar eclipse was in China in 21 B.C., and their notoriety has grown in more recent years as technology has allowed scientists to learn more about eclipses, Kirk said.
The next solar eclipse is set to occur in 2024, but Maryland again won't be one of the best areas to see a total eclipse. That isn't set to happen until 2099, according to Kirk.
"It puts in context our place in the solar system, [that] we are on a tiny little rock in outer space," Kirk said. "[You] can see the awesome beauty of the sun as the eclipse passes through, [it's] one of the best things you can see with the naked eye."
Date: Monday, Aug. 21
Best time to view locally: Between 1 and 3 p.m.
Where to find safety eyewear: Go to the American Astronomical Society's website http://bit.ly/2vUCWuH
Where to go: Viewing parties, NASA live streaming, Glenwood Branch library, 2350 Route 97, Cooksville, 1:30-3:30 p.m.; Savage Branch library, 9525 Durness Lane, 1:30-3:30 p.m.; Miller Branch library, 9421 Frederick Road, Ellicott City, 2-3 p.m.; Benjamin Banneker Historical Park and Museum, 300 Oella Ave., Catonsville.