Two students, who happens to be neighbors, made shadow plots on the same day. The students compare their plots and notice that their shadows are different in length and that the shortest shadow points in the wrong direction. How could you account for the differences in their shadow plots?
The equator must run between the houses of the two neighbors making the shadow plots.
Light rays from the sun are considered parallel to each other by the time they reach the earth. This is because of the distance and size of the sun. Light rays hitting the earth in Alaska and those hitting in Florida are traveling parallel to each other but strike the earth at different angles because of the curvature of the earth surface.
The length of the shadow caused by a gnomon (stick) used for a shadow plot is determined by the latitude (distance from the equator) of where the plot is being made. If two shadow plots are made at 10:00 AM, using identical length gnomons, in Maine and Florida, the shadow in Maine will be longer than the shadow in Florida. As you approach the equator, the length of the shadow at that same time gets shorter still. Once you cross the equator, because the stick is now basically tilted in the other direction (because of the curvature of the earth) the shadow will go in the other direction.