Use the given information to complete parts I and II. In your final answer, include all calculations.

Planet Earth has an approximate diameter of 1.2742 · 10 10 millimeters. The sun has a diameter of 1.391 · 10 6 kilometers.

Part I: Given that for every one kilometer there are 1,000,000 millimeters, which unit of measurement should be used to best represent the lengths of the sun and Earth's diameters?

Part II: Approximate how many times greater the sun's diameter is than planet Earth's.