Marking the International Year of Astronomy (IYA), Jeff Kanipe takes a look at the prospects of the �big four� major new telescopes [News Feature p. 18]. They have a tough act to follow, as a trawl through �Hubble�s greatest hits� reveals [Review Article p. 41]. The �Dark Skies Awareness� campaign is part of IYA 2009; Malcolm Smith argues the case for a transformation that would not only help astronomers but would also benefit human health and energy conservation [Commentary p. 27]. Also part of IYA 2009 is the celebration of 400 years of the telescope; Owen Gingerich tracks the link between technology and our changing world-view [Essay p. 28]. Robert Poole�s book Earthrise focuses on the psychological impact of the Apollo 8 image of Earth over the lunar horizon, though our reviewer feels that our attitudes towards our planet have not changed enough [Books & Arts p. 30]. �Hidden treasures� visits the Paris Observatory [p. 33] and astronaut Alan Bean talks about his moonscape paintings [p. 31]. In Futures, David Blair looks back on 2009 [p. 122] and in a Letter, Alyssa Goodman et al. reveal the importance of self-gravity in star formation [p. 63]. See the Editorial [p. 7] and visit www.nature.com/astro09 for more. COVER PICTURE: Hubble Space Telescope/Christian Darkin