| Uncovering Alcor's Secret | 17 Apr 2010 |
| Abstract | Location: Custer Observatory, Southold, NY |
| The Search for Extraterrestrial Intelligence in the 21st Century | 22 Jan 2010 |
| Abstract, Full Text | Location: Columbia University, New York, NY |
| Stardust to Sentience | 20 Oct 2009 |
| Abstract | Location: Mid-Hudson Astronomical Association, New Paltz, NY |
| The Arrow of Time | 28 Mar 2008 |
| Abstract | Location: Columbia University, New York, NY |
| Green Dragon in the East: Astronomy in Ancient and Imperial China | 1 Mar 2005 |
| slides (4.4 MB PDF) | Location: The Cooper Union, New York, NY |