Western Pennsylvania astronomers prepare for solar eclipse

Western Pennsylvania will get its first good look at a solar eclipse in more than two decades on Aug. 21, and astronomers throughout the region want to make sure people are prepared.

A solar eclipse occurs when the moon passes between the earth and the sun. The path of the eclipse is determined by the Earth's position relative to both celestial bodies.

The last time an eclipse was visible in this area was May 1994. The last total eclipse visible in the United States was in 1972.

“Pittsburgh's only going to have about 80 percent coverage,” said Amateur Astronomers Association of Pittsburgh President Ed Moss. “So we won't be able to see to total eclipse, but it will be close.”

The eclipse will begin at roughly 1:10 p.m. in the Pittsburgh region and will be visible for 2 hours and 44 minutes.

But people should be wary of how they view it, Moss said.

“There are special glasses you can buy, and there are also solar filters that you can put on a telescope,” he said.

John J. Smetanka, vice president for academic affairs, academic dean and assistant professor of astronomy at St. Vincent College, will visit 13 Westmore‑land County libraries in the weeks leading up to the eclipse to educate residents on why it occurs and how to view it safely.

“It's not that it's more dangerous to look at the sun during an eclipse, but you're tempted more to look,” Smetanka said. “You want to see that crescent, but even with 85 percent of the sun obscured, it's still way too bright to not damage your eyes.”

One interesting way to observe the eclipse's effect is to look at the shadow of a tree, which functions in a similar way to the “pinhole viewer” that can be created using a shoebox.

“The sun is round, and so typically you don't notice that large, round blobs of light are passing through the leaves of the tree,” Smetanka said. “During the eclipse, instead of round blobs of light, the tree almost functions as a multiple-pinhole projector, and you end up seeing crescent-shaped blobs of light.”

Both of the Pittsburgh astronomy group's observatories, Wagman Observatory in Deer Lakes Park and Mingo Creek Park Observatory in Finleyville, will be open during the eclipse, and each has telescopes outfitted with solar filters.

St. Vincent College will let visitors view the eclipse from 1 to 4 p.m. in the Sis and Herman Dupre Science Pavilion on the Unity campus. In case of inclement weather, viewing will be moved to the college's observatory and Angelo J. Taiani Planetarium.

Smetanka said he is enjoying the enthusiasm people have shown at libraries he has already visited.

“To have 20 or 30 people turn out in Scottdale or Vandergrift to learn about an astronomical event is great to see,” he said.

Patrick Varine is a Tribune-Review staff writer. Reach him at 724-850-2862, pvarine@tribweb.com or via Twitter @MurrysvilleStar.