which is close to the correct value (0.016710218). The accuracy of this calculation requires that the two dates chosen are along the elliptical orbit's minor axis and the midpoints of each half are along the major axis. As the two dates chosen here are equinoxes, this will be correct when perihelion, the date the Earth is closest to the Sun, falls on a solstice. The current perihelion, near January 4, is fairly close to the solstice of December 21 or 22.