Aadil Desai
First, the Moon’s distance from Earth varies over its orbit. Second, Earth’s elliptical orbit causes the Sun’s distance and apparent diameter to vary by about 3 percent from perihelion (closest approach) to aphelion (farthest approach). Near the sunrise and sunset terminators, the Moon’s shadow hits Earth’s surface at a steep angle. This geometry causes the shadow to move quickly with respect to the surface, which shortens totality’s duration.