August 2017 Eclipse over North America
One struggle with animating eclipses is trying to come up with the line of sight that best demonstrates the various motions and shadow shapes involved. The things I try to capture are the teardrop area of partial eclipse, the shortening then elongating ellipse of totality, the movement of the Moon’s shadows in the combined motions of the Earth orbiting the Sun and the Moon orbiting the Earth, and the Earth’s rotation, unfortunately in the same direction as the motion of the shadows. Here is the best I have been able to muster so far with the 2017 total eclipse over North America. This viewer of this scene is travelling in orbit along with the Earth with the line of sight pointing at London Ontario. The viewers position with respect to the Earth is fixed, so the Earth rotates below the viewer. The light purple shaded area with the straight edge is the 3D outer shadow cone of the Moon (or penumbra) travelling in space, within which someone looking at the Moon would see the Sun partially covered. The light gray elongated cone is the 3D inner shadow cone of the Moon (or umbra), in which a person looking at the Moon would witness the Sun being totally hidden. The dark purple teardrop on the surface of the Earth is where the penumbra comes in contact with the Earth. Here, people on Earth see a partial eclipse. The bright red ellipse racing across the Pacific, the United States and the Atlantic is the area of totality, where the umbra meets the Earth’s surface, and observers experience a total eclipse.