All stars change size over their lifetimes,
but the sun is currently very stable. Evidence indicates
the sun has a constant diameter of about 1.4 million
kilometers. The only reasonable explanation for the
change in the sun's apparent size is that Earth's distance
from the sun changes in a regular pattern.
1. How would the sun appear in the animation if Earth orbited it in a perfect circle?
2. Sketch the shape of Earth's orbit that you think explains the sun's appearance in the animation.