In a dream, you land on a planet in a location such that all the stars you can see rotate in circular arcs in the sky, and they do not rise or set; a star directly overhead (your zenith) remains stationary. You then walk in one direction a distance of 3000 km to a location such that the stars you now see all set and rise at right angles relative to the E-W horizons. What is the circumference of this dream planet