In 2009 the world celebrates the International Year of Astronomy to commemorate the 400th anniversary of Galileo’s use of a telescope to study the night sky. 2009 is also the anniversary of many other important dates in the history of science, such as the publishing of Kepler’s Astronomia Nova, Huygens’ Systema Saturnium, and the first moon landing. You can follow IYA2009 now on Twitter