Mark Hammergren, Ph.D. is an astronomer at the Adler Planetarium. His research interests include asteroids (particularly their shapes, compositions and internal structures), the effects of past asteroid impacts on Earth, and the history and sociology of the flying saucer phenomenon.
Hammergren is the Director of the Astro-Science Workshop (ASW), an NSF-funded summer outreach program for high-school students interested in astronomy. The ASW program is in its 42nd year and includes such distinguished alumni as Astronaut John Grunsfeld.
