Venus is never more than 47 degrees above the horizon at sunset. Does this tell us Venus orbits Earth?
The reason Venus never exceeds that angle from the sun is because it is orbiting the sun, inside of the earth’s orbit. It means that it never goes outside of the earth’s orbit, which would also preclude it being in any kind of earth orbit. Also, its motion, back and forth between these two points, is consistent with it moving in a circle of that diameter, around the sun. Mercury shows the same effect, only closer to the sun. Venus is not pulled into the earth’s orbit, but its orbit is very slightly perturbed by the earth’s gravity. And al, above me, is right in pointing out that it is the sun, not the horizon, that we are measuring from. Venus actually does appear to go all the way around us every day, just like every other celestial object. This is because of the earth’s rotation, though, and has nothing to do with Venus’ movement. The reason we rarely *see* it more than 47 degrees from the horizon is because that would be when the sun is up and the bright sky washes it out.
