[Chronicle]

Aug. 12, 1999
Vol. 18 No. 20

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    [space explorers]

    Students in the Space Explorers program study the Dunham Telescope here on the University campus.

    Space Explorers map the invisible universe in radio astronomy class

    By Steve Koppes
    News Office

    Even the Invisible Man would find it difficult to evade the inquisitive eyes of the Space Explorers.

    The Space Explorers, a group of 26 South Side middle school and high school students, recently made a map of the invisible universe. The exercise was part of a pre-collegiate radio astronomy class offered by the University’s Center for Astrophysical Research in Antarctica.

    Mapping the invisible universe only sounds impossible to those unfamiliar with the wonders of radio astronomy. Using the recently upgraded radio telescope sitting atop the Kersten Physics Teaching Center, the Explorers have detected objects in the sky that emit radio waves instead of visible light. The telescope could even have revealed the Invisible Man, had the creation of novelist H.G. Wells stepped in front of it.

    “People emit radio waves simply because they have temperature—they are thermal sources,” said Daniel Reichart, a graduate student in Astronomy & Astrophysics and a Space Explorers teacher.

    “Although most of our energy comes out in the infrared, some of it comes out in the radio. If one gets right in front of the telescope, the radio emission of a single person is enough to pick up,” Reichart explained.

    Astronomers still peer through optical telescopes in the dark of night for some types of research, but "the meat and potatoes of astrophysics right now is radio astronomy," said Randall Landsberg, CARA’s Director of Education and Outreach.

    Undergraduates taking advantage of the new astronomy concentration in physics also will use the Kersten telescope, Landsberg said. And the department plans to make it available to small colleges and high schools to augment the teaching of astronomy.

    “The ideal thing is to make this telescope remotely controllable through the Internet,” Landsberg said. “The telescope then could be used 24 hours a day, seven days a week.”

    Unlike optical telescopes, radio telescopes can operate around the clock, in daylight or at night, and even in cloudy skies. In fact, the Kersten radio telescope and its computers collected data for 24 consecutive hours one weekend in April during the Space Explorers’ effort to map the invisible universe. Members of the Space Explorers monitored the telescope in shifts along with a group of undergraduate students and members of the Ryerson Astronomical Society.

    “The radio sky is very different from the optical sky you see at night,” Reichart said.

    While the optical sky is full of stars like the sun, the sun is the only star close enough to Earth for the radio telescope to detect. The telescope also detected an assortment of celestial objects, including supernovas, which are exploding stars; quasars, the most distant known objects in the universe; and stellar nurseries where stars are born.

    Astronomers already have mapped many objects in the sky. The students used those maps to check their own data but also the accuracy of existing maps, said Damien Wilson, a junior at St. Ignatius College Prep.

    “You have to watch out for all the static and different intrusions that you get in the data,” Wilson said. These intrusions include buildings, humans and the ground, which all emit radio waves that the telescope records when it is aimed near the horizon.

    The point of the exercise is to teach the Explorers both how to use the telescope and the concept of the celestial sphere, the sphere of stars that appears to surround the Earth, Reichart said. “The educational value of the celestial sphere is rather high,” he said. “It’s a complex, three-dimensional, rotating geometry problem.”

    Ancient astronomers believed stars were attached to the invisible sphere and that they rotated once a day around a fixed point near Polaris, the North Star. Astronomers eventually realized the rotation of the Earth’s surface made it appear as though the stars were moving rather than the planet from which they were viewed.

    Nevertheless, the celestial sphere remains a useful concept for mapping the sky. Astronomers can use it to precisely map locations of stars visible from any point on Earth by right ascension, which corresponds to longitude on a world map, and declination, which corresponds to latitude.

    The Space Explorers charted the data they collected onto a model celestial sphere measuring 12 feet in diameter, which sits at the top of the stairs on the Kersten Center’s third floor.

    “Nothing beats hands-on learning,” Reichart said.

    Ashley Garrison, for one, has been unable to resist the pull of astronomy. The Sutherland Elementary School eighth-grader has especially gravitated toward the study of black holes. She even wrote a book about them and entered it in the Young Authors Contest.

    “My friends just thought I was so crazy,” Garrison said. “I didn’t win or anything, but I read that book a lot. I like it.”