Elementary Astronomy (2000, 2013) — a book I wrote for teachers (and parents) of students in grades K-6, explaining the basic astronomy concepts encountered in those grades. The current edition is available as a FREE pdf.
Life in the Universe: The Abundance of Extraterrestrial Civilizations (2008) — a text I wrote for our AST 115 (Life in the Universe) general education course.
Notes on Stellar Astrophysics (2013) — a text I wrote for students in our senior-level astrophysics sequence: AST 420 (Stellar Astrophysics) and AST 421 (Stellar Structure). The current edition is available as a FREE pdf.