How much does the distance between the earth to the sun vary?

Question

I keep reading that the "average" distance is 92,958,350 miles (1 AU). If that's the average, how much variance is there, and why?

Answer 1

The sun also contracts and expands over a period of ten years.

Answer 2

The Earth actually has an irregular, oval-shaped orbit around the sun (unlike the circular shape we all think it is). The Earth is closer to the Sun in January (that's right, January) and farthest from the sun in July. The reason we have seasons the way we do is because the Earth is tilted, which affects how the sun's rays hit the Earths' surface. You can find more information about the seasons here: http://www.msnbc.msn.com/id/3077384/

So, to answer your original question, a study on our distance from the Sun was done in 2000. It was found that at perihelion (the spot where we're closest to the Sun) we were 91,405,436 miles from the Sun, while at aphelion (the spot where we're farthest) we were 94,511,989 miles from the Sun. As you can see, the distance doesn't change a whole lot really (just a few mere million miles), so the change in distance doesn't affect our seasons at all - it's all in the tilt of our planet, which I explained earlier.

You can find more information about all this here: http://www.windows.ucar.edu/tour/link=/k...

Edit: You're welcome! :)