Imagine a straight line that contains both the center of the sun and the center of the earth. This line passes through a point on the surface of the earth that is between those two points. As the earth rotates, this point moves west, forming a kind of line on the surface of the earth. What is this line called? I was south of it once while visiting Aruba and thought it was so neat to see the sun apparently move from right to left across the sky instead of the other way. Thanks!