Check this SkySafari 3 app for iPhone/iPad/iPod for free
iTunes brings in another free app called SkySafari 3 for iPhone, iPad and iPod. With 5 stars rating, 2012 hot product macworld, 2010 best of show winner and called as the the best of all the star chart apps for iOS, SkySafari 3 shows you 120,000 stars, plus 220 of the best known star clusters, nebulae, and galaxies in the sky. It displays the Solar System's major planets and moons using NASA spacecraft imagery and includes the best known asteroids and comets. SkySafari 3 accurately shows you the sky from any place on Earth at any time up to one hundred years in the past or future.