Keep Your Eyes on the Skies

August 19, 1999

SEARCH THE GAZETTE

HARVARD GAZETTE ARCHIVES

By Alvin Powell
Contributing Writer

Adam Langer looks through a telescope at the Science Center observatory as part of an astronomy course taught by Rosanne Di Stefano, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics. Photo by Tony Loreti

The telescope was ready, the observatory's dome was open, but the sky was closed for business on top of the Science Center one recent Thursday.

Though Venus had been bright on the darkening horizon earlier in the evening, the planet faded behind a thickening blanket of clouds, frustrating astronomy students’ efforts to gaze at the night sky.

"It looks like no observing tonight," teaching fellow Alessandro Massarotti told Zvi Rosen, a student who had followed him up to the observatory where the Loomis-Michael telescope stands.

Rosen, an incoming freshman at Yeshiva University and a student in Harvard Summer School’s Fundamentals of Contemporary Astronomy: Stars, Galaxies, and the Universe, took the news in stride.

After all, astronomy is an observational science. Bad weather is a part of life.

"I enjoy astronomy because it shows us the sheer physical majesty of the universe," said Rosen, whose amateur astronomer father got him interested in the stars.

Though the weather has canceled some of the observing sessions this summer, students in the course have seen many bodies inside and outside of our own solar system: the moon, Venus, Mars, and some more distant structures, such as double stars and globular clusters.

Rosen is among approximately 60 students from a variety of backgrounds taking the introductory astronomy course this summer. Students come from across the United States and include high school, undergraduate, and graduate students.

Though to many people, astronomy is observing, actual observation is just a small part of the class.

Students have to take turns at the telescope, but while they’re waiting they can soak up the atmosphere under the observatory dome.

Constellations are painted on the circular walls and the long, white telescope is complemented by a ladderlike wooden contraption that rolls around the room supporting the observer’s wooden chair. The chair, in turn, rides up and down the wooden structure on rails, permitting the observer to see, regardless of the telescope’s position.

While students like Rosen are eager to get their turn in the wooden chair near the telescope’s eyepiece, a computer lab downstairs provides simulations of observing sessions that allow students to look at stars and galaxies much farther away and more mysterious than the planets and the moon that can be seen from the Science Center’s roof.

Still, to budding astronomers, there’s something special about seeing it with your own eyes.

"When I was going to be a freshman in high school, I went to the Adirondacks. Just going there and seeing the Milky Way, it was amazing," said Nadia Bartolucci, another student in the class. "[The class] is a challenge, but a challenge I don’t regret getting myself into."

Rosanne Di Stefano, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics and the course’s instructor, acknowledged that the class is tough. In addition to the twice-weekly 6 to 8:30 p.m. lectures, students must attend a two-hour computer lab/observing session once a week.

And, though physics is not a prerequisite, the course does cover technical concepts such as relativity and quantum mechanics.

"It’s a fairly challenging course, even though we don’t use calculus," said Di Stefano, who is teaching the summer course for the third time.

The popular conception of astronomers has them peering at the sky through telescopes, but much of today’s observing is done using sophisticated instruments that detect radiation other than visible light. This approach provides many different images of the universe and provides a picture far more complete than that available from what we can see.

Di Stefano said the class works its way outward, starting with general concepts such as luminosity and leading into discussions of stars and stellar lifetimes. Students then move on to the structure of galaxies and to a discussion of distant galaxies and the structure of the universe.

Mixed in with those broader classroom topics are specifics such as galactic collisions — the Milky Way is apparently careening toward the Andromeda galaxy — X-ray binary stars, black holes, and the scientific instruments used to observe them, such as the recently launched Chandra satellite observatory, which will examine the universe in X-rays.

"My reason for designing this course is to make the idea of astronomy as it is done today — research in astronomy — real to students," Di Stefano said.

A recent discussion, for example, dealt not only with past scientific discoveries, but with ongoing research — the search for dark matter.

Dark matter is undetectable because it emits no measurable radiation. And if there is enough of this material — exotic particles or low-mass concentrations of more familiar matter, for example — then gravity will eventually cause the universe’s expansion to reverse itself, collapsing it and, perhaps, sparking another Big Bang. If there isn’t enough dark matter, then gravity will be too weak and the universe will continue expanding.

Observers are currently searching for dark matter by looking for evidence of microlensing where the dark matter deflects light from distant sources. From these deflections, reseachers can infer the presence of dark matter.

Another way Di Stefano attempts to make astronomy real for her students is by inviting guest lecturers to talk about their current research. Guest lecturers this summer have included Matthew Holman, who spoke about asteroids, Leonard Strachan, who spoke about solar research, and Eric Woods, a teaching fellow in the course, who spoke about his doctoral thesis research into gamma ray bursts.

Some of Di Stefano’s own research involves searching for distant planets. Too small to be seen, the planets discovered so far have been detected indirectly, by looking for a wobble in a star’s rotation caused by a planet’s pull. Di Stefano works with a technique called microlensing, which can detect planets when they deflect light from more distant stars. She also studies binary stars that are so close together they transfer mass from one to the other, as well as other high-energy processes.

Like her student Nadia Bartolucci, Di Stefano remembers the first time she was enamored by astronomy. It was as a girl watching her first planetarium show.

"I was fascinated as a child," Di Stefano said. "[The planetarium show] started with them dimming the lights. And as the lights dimmed, I began to see stars in a way that, as a child growing up in New York City, I had never seen before."

Di Stefano’s Ph.D. is in high-energy physics, focused heavily on theory. After a while, however, she felt dissatisfied with work that would likely not be connected to experiments or observations within her lifetime.

"I went back to my first love and have found it very exciting to be able to make predictions which are later tested," Di Stefano said. "To me it seems the most valuable things we can give students are the insights and the realization that physics and astronomy are living fields."