The great American eclipse is coming.
On Aug. 21, the moon will cross in front of the sun, casting a shadow along a path stretching from Oregon to South Carolina, pitching those in that narrow band of totality into darkness for 2 ½ minutes while the solar corona blazes in wispy glory around the blackened disk of Earth's only satellite.
At least a partial eclipse will be visible from all the continental United States and parts of Canada and Mexico. In the skies above Carroll County, the moon will occlude 80 percent of the sun.
"You are going to see the sun go from a nice, yellow ball down to a pretty thin crescent," said Skip Bird, outreach director with the Westminster Astronomical Society.
The key thing about that thin crescent sun, and the fully covered sun in the path of totality for that matter — you can't look at it with your naked eyes. A proper filter, eclipse glasses or other viewing technique is necessary to protect your eyes from serious damage.
That's why Bird is presenting on the eclipse in a free Tuesday event at the Mount Airy branch of the Carroll County Public Library.
"It's going to be a program with a little bit of safety, a little bit of history, why the eclipse is unique," he said. "If it is nice outside, we will also have my telescope with a solar filter on it so we can look at the sun."
Bird will also be handing out eclipse glasses, not unlike the paper specs you might receive to view a 3-D movie, but with special filters — like that used on his telescope — to make viewing the eclipse safe.
There will also be demonstrations on how to make eclipse art projects, cardboard eclipse viewers — perfect, Bird said, for children too young to safely use eclipse glasses — and "lots of things that that families can do on the day of the eclipse."
Bird's solar eclipse presentation will begin at 3 p.m. Tuesday, July 25, but on the day of the eclipse itself, he will be on the path of totality in Lincoln, Nebraska, and he advises anyone who can make it to a point along that path do so. NASA provides a variety of maps online at eclipse2017.nasa.gov/eclipse-maps.
"This is a once-in-a-lifetime event. This will be my fifth eclipse and it's the only one that's been in this country," Bird said. "All the rest have been elsewhere."
The next total solar eclipse visible from the U.S. will be in April 2024 and will cross through the Midwest, a time and course Bird said could make for unpredictable viewing.
"The weather prospects are worse. It's April and there could be a front stretching from Texas to Michigan," he said. "There's a good chance it will be raining or snowing."
The next shot after 2024 isn't until Aug. 21, 2045.
For those who simply cannot make a trip to the path of totality, the 80 percent coverage to be seen from Carroll County is still worth checking out, Bird said. If he can find members of the Westminster Astronomical Society who are also sticking around, there may be eclipse viewing parties announced on the club website at www.westminsterastro.org.
All the Carroll County Public Library branches will be open for at least eclipse viewing, and may include some impromptu talks on the event, according to library Director of Community Engagement Dorothy Stoltz.
"We encourage people to stop in on Aug. 21 from noon to 3 p.m. to pick up a pair of [eclipse] glasses and — weather permitting — join librarians in viewing this wonderful event," she said.
The eclipse glasses will be available while supplies last, but Stoltz hopes interest in astronomy and geosciences will persist long after the day of the eclipse.
"We hope to tap the excitement of the Aug. 21 solar eclipse and encourage people of all ages to wade through library books and other resources on astronomy," Stoltz said.
"This is the type of event that may start a lifelong interest in the planets and stars."
If you go
What: Solar Eclipse 2017 (preview event)
When: 3 p.m. Tuesday, July 25
Where: Mount Airy branch of the Carroll County Public Library, 705 Ridge Ave.
For more information about the eclipse on Aug. 21, visit eclipse2017.nasa.gov.