In 2009 the Observatory joined in celebrating the International Year of Astronomy (IYA2009) being celebrated through the initiative of the International Astronomical Union and UNESCO. It has been honored the 400th anniversary of Galileo’s first telescopic observations, one of the epoch-making events at the beginning of modern science.

In 2008 the Observatory organized for the following IYA2009 events:

• Together with the Vatican Museums and Italy’s National Institute for Astrophysics the Observatory, an exhibit at the Vatican Museums featuring telescopes down through the centuries. The exhibit was opened in the autumn of 2009.
• Together with the Pontifical Academy of Sciences, a Study Week on Astrobiology had been held at the Academy 6-10 November 2009.
• A meeting 21-26 June 2009 of Vatican Observatory Summer School alumni on the theme of “Astronomy: A Stimulus to Dialogue on Humanity’s Common Concerns.” The meeting was at the Istituto il Carmelo Conference Center at Sassone, Italy, near the Observatory headquarters at Castel Gandolfo. In addition, the Observatory is one of the sponsors of the following IYA2009 international

Conferences:

• The Galileo Affair: A Historical, Philosophical, and Theological Re-Examination, 26-30 May 2009 at the Istituto Stennsen in Florence.
• VI Conference on the Inspiration of Astronomical Phenomena, 18-23 October 2009 in Venice.