Solar System
- March 20 Spring Equinox Sunset Watch — 2019 (Mar 2019)
- September 19 Fall Equinox Sunset Watch — 2018 (Sep 2018)
- June 16 Summer Solstice Sunset Watch — 2018 (Jun 2018)
- December 21 Winter Solstice Sunset Watch–2017 (Dec 2017)
- September 22 Fall Equinox Sunset Watch–2017 (Sep 2017)
- Spring Equinox Sunset Watch – 2015 (Mar 2015)
- How Many Times Can One Spacecraft Leave the Solar System? – 365 Days of Astronomy (Feb 2014)
- Kepler Mission: Basic Background (Jun 2010)
- Answering Questions: Life on Other Planets? (Dec 2009)
- Planets Cards! (Mar 2009)
- Comet Lulin (Mar 2009)
- Planetary Alignment (Aug 2008)
- Retrograde Motion (Jul 2008)
- The Ugly Ducklings: Composition of Uranus and Neptune (Jun 2008)
- A Series of Questions (II) (May 2008)
- Asteroid 2007 TU24 NOT Going to Hit the Earth (Jan 2008)
- A Series of Questions (I) (Feb 2007)
- What is a Planet? (Aug 2006)