Clear skies this weekend, so we drove 30 miles out of the city, and enjoyed a good view of the Milky Way. One thing that confused me, though: the band seemed to have a slight curve to it as I followed it across the sky. Since the plane of the galaxy is flat, I would've expected the Milky Way to appear as a straight line across the sky when viewed with the naked eye. Is there something about our atmosphere that causes it to refract into a curve? Or was I experiencing some kind of optical illusion, perhaps having to do with the curvature of the Earth?