If a space probe were sent into orbit around the sun that brought it as close as 0.5 AU to the sun and as far away as 5.5 AU, what would its orbital period be?

Can I use Kepler's 3rd law for this? I'm not sure how to take into account both AUs...

2 answers

Yes, you can use Kepler's third law, but instead of the radius (which of course only applies to circular orbits), you must use the average of the closest and the farthest distance from this sun.

That distance, which astronomers call the "semimajor axis" of the ellipse, is 3.0 AU in this case.
Great, thanks. :)