Rosen is among approximately 60 students from a variety of backgrounds taking the introductory astronomy course this summer. 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. When I was going to be a freshman in high school, I went to the Adirondacks. 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. 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.
Dark matter is undetectable because it emits no measurable radiation.
Observers are currently searching for dark matter by looking for evidence of microlensing where the dark matter deflects light from distant sources. Another way Di Stefano attempts to make astronomy real for her students is by inviting guest lecturers to talk about their current research. 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.