The International Year of Astronomy 2009 is a worldwide celebration of astronomy and its contributions to society and culture. It marks the 400th anniversary of Italian scientist Galileo Galilei turning a telescope to the sky. This was the beginning of modern instrumental astronomy and a milestone in the history of science.

Organisers in 137 countries are running activities throughout the year aimed at establishing collaborations between professional and amateur astronomers, science centres, educators and science communicators. The goals of IYA in Australia include raising awareness of Australia's contributions, strengths and role in astronomy and encouraging young people in particular to engage with the natural world through astronomy.