In 1609, Galileo Galilei turned his telescope to the night sky and began a series of observations of the cosmos. These observations, together with the work of Johannes Kepler and other scientists of the time, revolutionized our understanding of the universe and the process by which we do science. The United Nations General Assembly has proclaimed 2009 the International Year of Astronomy (IYA) in recognition of the 400th anniversary of Galileo's historic achievements. This month's Idea Bank provides ideas and resources to help you commemorate this special occasion in your science classroom. (Contains 1 figure.)