News From Terre Haute, Indiana

August 11, 2011

MARK BENNETT: This is the perfect time to lie on your back staring at the sky

Mark Bennett
The Tribune-Star

TERRE HAUTE — August should be national hammock month.

The night sky turns into an astronomical kaleidoscope in the year’s eighth month. And, there is no better way to gaze at it all than supine (flat on your back) in a hammock. No remote control or iPhone is necessary. Humans are powerless to start or stop celestial displays, anyway. Just exhale and look up. The heavens will take care of the rest.

The best moments to be a hammock-bound amateur astronomer arrive during the overnight hours of this Friday and Saturday. That’s when the Perseid meteor shower — the largest and most reliable annual meteor shower — reaches its peak. Thin flares of light streak across the sky, adding movement to the still glow of the stars. On average, 90 meteors per hour are visible, in the right conditions.

“The Perseid is probably the most spectacular and the most famous,” said Richard Ditteon, professor of physics at Rose-Hulman Institute of Technology and director of its Oakley Observatory.

Thus, it’s worth staying up late to see. Brew some coffee. The optimum viewing times for this year’s Perseid are estimated to be around 2 a.m. both nights.

To the first-timer, the term “meteor shower” may conjure images of Armageddon. Rest assured, boulders do not hurtle toward Earth, raining fire down upon us this weekend.

The streaking images during the Perseid are indeed meteors, but as tiny as grains of sand. “If you get a boulder,” Ditteon said of meteor sizes, “you’re going to get something that’s visible [even] in daylight.”

Instead, the August event involves much smaller objects. “What you’re seeing is debris left over from a comet named Swift-Tuttle,” Ditteon explained. “It just so happens, the Earth passes through that debris cloud every August.” The debris from the comet’s tail gets more dense as the planet bisects the middle of the cloud, which is why the monthlong Perseid sparkles brightest in mid-August.

Despite their granular size, those space particles enter Earth’s atmosphere at 40,000 to 50,000 miles per second, burning along the way and then vaporizing. This particular meteor shower gets its name because it appeared to radiate from the constellation Perseus, according to the popular astronomy website www.space.com. In Greek mythology, Perseus beheaded Medusa, whose snake-filled hair was so hideous it turned to stone anyone who laid eyes upon it. Eyeing the Perseid meteor shower involves no such danger. A few tips help, though.

This year’s Perseid peak might be a bit less brilliant because the moon will be full and bright. “That [lunar illumination] makes it more difficult to view the fainter objects,” Ditteon said. Nonetheless, meteor-gazers likely will see more activity than on any other nights in 2011. The ideal locations would be miles from pervasive artificial lights, especially around downtown Terre Haute or commercial areas. “Get as far away from Kmart as you can,” Ditteon said, suggesting spots in the countryside.

Once you’ve chosen a location, look toward the northeast (because they tend to come from that direction), but don’t focus on one point, he added. Rather, stare at the sky as you would the entire field from a top-row seat in a major-league baseball park. Rely on your peripheral vision to spot the meteors, which occur randomly in various parts of the sky and often in bunches. Binoculars make it easier to spot fainter meteors but limit a broader field of view.

Backyard astronomy is tougher in the 21st century because artificial lights are stronger and more prevalent. “That’s one of the bad things about our modern society,” Ditteon said. “We’ve got a lot of light pollution. The average Joes don’t know how beautiful the night sky can be.”

Ditteon has studied space extensively. A native of Anderson, he worked on NASA’s Viking program, which sent an unmanned probe to Mars in the 1970s. He’s taught at Rose-Hulman for more than a quarter-century, and has guided the observatory since the early 1990s. Inside that facility is a Ritchey-Chretien telescope sporting a lens a half-meter in diameter. When the college’s classes resume Sept. 1, Ditteon will be educating young engineers on the activity in space.

For us average Joes, the August meteor shower gives us our astronomy lesson and catches our eyes. (If we keep them open late enough to see it all.) “People are just curious,” Ditteon said of fascination with astral phenomena, such as Perseid. “They want to know what’s going on.”

My layman’s advice — find a hammock and just open those eyelids.

Mark Bennett can be reached at (812) 231-4377 or mark.bennett@tribstar.com.