Why are the rotation periods of some of the planets (like Venus) a negative number?
If you go to the website and click on the words “Rotation Period” in the left column, you can get the answer: Rotation Period (hours) – This is the time it takes for the planet to complete one rotation relative to the fixed background stars (not relative to the Sun) in hours. Negative numbers indicate retrograde (backwards relative to the Earth) rotation. If you are asking why there is retrograde motion, we have already answered that question on our site. See Why Don’t All the Planets Spin the Same Direction? Dr. Eric Christian (December 2003) • Shape of Planetary Orbits What is the shape of the path traveled by the planets around the Sun? I know it’s elliptical, but is it exact? I would tend to believe it is more of an egg-shaped path than a perfect ellipse. What are the dimensions of Mars’ path around the Sun? The orbits of the planets are ellipses, as discovered by Kepler. An ellipse is defined by its major axis (D) and the distance between the two foci (F). The eccentricity (e) is
