The Johns Hopkins Gazette: November 8, 1999
November 8, 1999
VOL. 29, NO. 11


Observatory Offers Weekly Celestial Spectacle

With a new telescope in place, Friday night's public viewings resume

By Michael Purdy

Johns Hopkins Gazette Online Edition

The light races across nearly 800 million miles of space, passing by Jupiter, the asteroid belt, Mars and the moon. It plunges through the thin veneer of atmosphere surrounding the Earth, passes a series of powerful lenses and mirrors, and splashes down, a bit more than an hour after it started, on its final destination: a human retina.

And for the lucky few gathered in the observatory atop the Bloomberg Physics and Astronomy building at Homewood, Saturn shimmers in the night, its rings resplendently tipped over for a breathtaking view.

When the expressions of delight subside, Alin Tolea, an astronomy graduate student, says, "Look toward the outer edge of the rings and tell me what you see."

It comes and goes and wobbles a little, almost like a spot on the eye, but ... .

"There's a black line there, right near the edge," says the man at the telescope.

"Exactly right!" Tolea exclaims, clearly delighted. "That's the Cassini division, which was thought to be a space between the rings but is actually four darker rings."

Welcome to opening night at the Maryland Space Grant Consortium's Observatory, the first return to public viewing hours since the old telescope was loaned away and a new one installed. The few stragglers who lasted past 10 p.m. are getting the Gas Giant Special--spectacular views of both Jupiter and Saturn.

"We study the stars all day, and it's nice for us to come out and look at them," says Claudia Kretchmer, observatory astronomer and first-year astronomy graduate student.

Kretchmer runs the public viewing hours, which take place every Friday, weather permitting (call 410-516-6525 after 6:30 p.m. on Fridays to check the status of that night's public viewing hours). And she does requests--if you want to see it, and it's up that night, she'll find it for you. Sessions last approximately from 7:30 p.m. until the last lonely visitors wander off, smiling and quiet, into the night.

Opening night started a little bumpy. Viewing conditions weren't the greatest, with hazy skies and, as usual, the bright lights of Homewood Field dominating the sky to the northeast. There were also some problems with telescope control. Earth's rotation causes the stars in the night sky to spin overhead, so the telescope's targeting computer needs both a precise star chart and the exact date and time to automatically find and track stars and other targets. Kretchmer and Tolea quickly learned that one or more of those factors were out of alignment, leaving them only the old-fashioned methods: Think of something interesting to look at and find it yourself. Kretchmer and Tolea looked at each other. Albireo? Albireo.

After a quick run to fetch a star chart and a few minutes of pointing, alignment and focusing, the 12 guests were taking turns looking at a binary star in the constellation Cygnus while Kretchmer and Tolea gave a sigh of relief.

"We reset the computer's tracking system based on our fix on Albireo," Kretchmer explained. Like seasoned impresarios, they had fixed a difficulty while at the same time producing something entertaining for the audience.

The wonders that followed included a ring nebula and several star clusters. As they moved from target to target, Kretchmer and Tolea chatted with their visitors about both basic astronomy and the latest findings in the news.

The stadium lights went out at 10 p.m. to cheers from those left in the observatory, and a request came in for planets. Kretchmer said Jupiter and Saturn were up but offered a caveat, warning that the view might not be all that spectacular, given the viewing conditions.

"The best nights for viewing are the coldest, driest ones," she said. "As you magnify the light coming in from space, you also magnify Earth's atmosphere, and that can cause fuzziness or jumpiness in the image.

"Also, we have to contend with heavy light pollution in the sky from unshielded Baltimore street lamps," Tolea said.

However, Jupiter was outstanding--several colorful bands of gas on the planet were visible, and four moons could be seen, strung out in an amazingly straight line on either side of Jupiter.

"I think I see the Great Red Spot!" one viewer exclaimed, referring to a colossal storm that has been prominent on Jupiter for centuries. "But it's kind of pale ... ."

"It's more of a Great Yellow Spot now," Tolea said. "Its color has been fading for years.

Later, as the spectators express their amazement at the beautiful spectacle of Saturn, Kretchmer reminisces about the first time she found Saturn in a telescope and showed it to her mother.

"She made me bring the end of the telescope back down so she could look at it," she says, laughing. "She thought I'd put a picture at that end."

Tolea, meanwhile, is sizing up the next target.

"See that cluster of stars there?" he asks a visitor, pointing to the Pleiades. "How many do you see?"

"Four," the visitor answers. "No, five."

"Now," Tolea says, punching in the coordinates on the computer, "take a look at this ... ."