Dan Malerbo expects 80 to 100 people to gather on the North Shore on Wednesday to take part in a sky-watching ceremony of a type that dates back to our earliest ancestors.
"One thing our ancestors did well was observe the heavens," says Malerbo, the education coordinator at the Henry Buhl Jr. Planetarium at the Carnegie Science Center on the North Shore.
Modern-day astronomy enthusiasts will be doing the same sort of observing that the educator believes led to the creation of the English shrine Stonehenge. They will be watching a total lunar eclipse, the last one until March 2007.
"They are very predictable," Malerbo says of the eclipses. "The stargazers who put together Stonehenge did it as a way of predicting them, our historians believe."
Predictable and relatively common, yes. But steadily regular, no.
Total lunar eclipses are more common than solar eclipses, Malerbo points out, but take breaks in their predictability. The upcoming event is the last in a cluster of four that began in May 2003.
The next group will begin in March 2007.
Comparatively, the next solar eclipse won't take place until 2017, he says.
Lunar eclipses occur at full moon when Earth's satellite passes through the planet's shadow. Partial eclipses occur when the Earth blocks part of sunlight reaching the moon. Total eclipses take place when the umbra -- or inner shadow of the Earth -- blocks all light, Malerbo says. Well, most of it, at any rate.
The educator goes on to explain because the sun is so much bigger than the Earth, some of the light spills over and is filtered by the atmosphere, giving the moon a colorful glow.
That filtration will block out light from the blue range, giving the moon a reddish tint. He says particulate matter in the atmosphere at any given time also changes the illumination. He says, for instance, elements from Mt. St. Helens, the volcano in Washington, could affect this viewing.
Malerbo also says urban light -- the glow centered on cities -- can alter the appearance. He points out the Amateur Astronomers Association of Pittsburgh will have eclipse watches at two sites that are a little removed from the city's shine.
The club is holding sessions at the Nicholas E. Wagman Observatory in Deer Lakes Park, Allegheny County, and the Mingo Creek Park Observatory in Washington County.
"There is a dedicated core of folks who show up for these things," he says. "There is a rich tradition of astronomy in the Pittsburgh area." Additional Information:
Details
Total lunar eclipseWhere and when: 8 p.m. Wednesday, Nicholas E. Wagman Observatory, Deer Lakes Park and Mingo Creek Park Observatory, Washington County. (724) 224-2510; 9 p.m. Wednesday, Henry Buhl Jr. Observatory, Carnegie Science Center, North Shore. (412) 237-3336.
Admission: Free.
