I saw this physics phenomenon on the concrete during the middle of the day in April. This mix of oil and water was in the parking lot of a local restaurant. The oil had leaked from a car and then mixed with water that was already on the surface. This colorful phenomenon is called thin film interference. This photo is unique because each of the small puddles are separate and different colors rather than being one large puddle, like most photos of thin film interference. There is a layer of oil that is on top of each mini-puddle of water, and when sunlight hits the puddle, some light gets reflected off the top surface, and some refracts through and gets reflected off the bottom surface of the thin film of oil. The interference between the two reflected light rays results in the various colors seen in the picture. The difference in color of each of the little puddles is due to varying depths of water and oil, and different angles of the rays hitting the puddles. Finally, though this picture is pretty cool, the physics is even cooler.