A phenomenon known as "Manhattanhenge" will make its biannual appearance before sunset this evening in New York City. The event occurs when the sun perfectly aligns itself down the middle of any east-west street in Manhattan, bringing people outside in masses to try to get pictures of the occurrence. Manhattanhenge occurs twice per year — once at the end of May and again at the beginning of July — as the sun's position in the sky changes as the seasons do the same. Wikipedia has a great graphic on its site explaining how the phenomenon occurs. On the summer solstice, the sun rises in the northeast and sets in the northwest. On the winter solstice, the sun rises in the southeast and sets in the southwest. As we approach the summer solstice, the sun is in the right spot this evening to set with perfect alignment along Manhattan's east-west thoroughfares. Of course, it's common sense not to stand in the middle of the road to take pictures, but you know someone's gonna do it anyway. Stay tuned for tomorrow's post, "Pictures of People Getting Hit by Cars While Taking Pictures of Manhattanhenge. "[Image via AP]