The positions of the stars in the night sky as seen over the Caspian Sea in northern Iran on January 29, 2009 at 23:31 (11:31 P.M.) local time. Image BN4317 shows the stars as seen from the same location one hour earlier, demonstrating the apparent change in star positions that occurs over time as a result of the earth's rotation. (Image BN4320 shows the same image with constellation lines).