Sun at Perihelion and Aphelion
July 04, 2004
Presented here are two photographs of the Sun, taken approximately six months apart from Madison, Wisconsin, by science teacher Art Camosy and myself. The first image was captured when the Earth was close to aphelion -- the point when Earth is farthest away from the Sun during its year-long orbit (in early July). The second was taken within a few days of perihelion -- when Earth is closest to the Sun (in early January). Our goal was to use these images to supplement a unit on the seasons taught to high school freshman science students. These images should help dispel the common misconception that summer occurs when the Earth is closest to the Sun. Rather, the seasons result from the Earth's constant tilt of 23 1/2 degrees. The north pole faces more Sun-ward during the portion of the Earth's orbit when it's furthest from the Sun but faces away from the Sun when it's closest to it. The Earth-Sun distance is approximately 147.5 million km at perihelion and 152.6 million km at aphelion.