iPhone Apps: SkyVoyager and SkyGazer for iPhone for free

SkyVoyager is a powerful planetarium program for the iPhone and iPod Touch. It is designed for both beginners and advanced users. It contains a database of 300,000 stars to 10th magnitude, and 30,000 deep sky objects, including the entire NGC and IC catalogs. It renders the planets and moons in detail, using NASA mission imagery, and includes a database of several hundred asteroids, comets, and artificial satellites.

SkyVoyager accurately shows the sky from any location on Earth, at any time up to 100 years in the past or future. It is a precise astronomical calculator, computing the positions of solar system objects to sub-arcsecond precision with the latest JPL planetary ephemerides.