It is 400 years since Galileo Galilei looked at the heavens through a telescope and changed our view of the universe for ever. In celebration and to stimulate worldwide interest in astronomy and science, the International Astronomical Union (IAU) and UNESCO have initiated the International Year of Astronomy 2009 (IYA2009).

Particle and nuclear physics may deal with the smallest components of matter, but both have strong links with astronomy – the news story above is just one example. This issue of CERN Courier celebrates IYA2009 with this and several longer articles. Nobel laureate George Smoot considers the exciting times in modern cosmology (Cosmology's golden age), while features on Borexino and MAGIC (Borexino homes in on neutrino oscillations and A MAGIC touch brings astronomical delights) look at two of the many experiments in the new field of astroparticle physics. Lastly, Viewpoint (Big Science, bigger outreach) considers a valuable message these "big" sciences offer to the public at large.