Astronomers have long known that sunspot numbers vary over a cycle that averages about 11 years. But do these cycles influence Earth's climate? And what about the longer term? Could the measured global warming of recent decades be a result of increased solar energy output? Freelance writer Kristina Grifantini explores these issues in the cover story of the March 2009 issue of Sky & Telescope.

In conjunction with the article, S&T Editor in Chief Robert Naeye interviewed Judith Lean of the U.S. Naval Research Laboratory. She's a leading authority on the Sun-Earth connection and a member of the National Academy of Sciences.

You can listen to the interview by downloading this 8 MB MP3 file.