the speed of a planet in its orbit
The average orbital speed of a planet or other object in orbit  round the Sun is propotional to the reciprocal of the square root  of the average distance from the Sun. â¦  V is proportional to 1/ sqrt (D)    This can be derived from Kepler's laws of planetary motion,  published in 1609 and still in use.o. The farther away you get from the sun, the slower the planets orbit. (and the sun looks smaller!). By the way, even if the planets were all moving at the same speed, they â¦ still wouldn't be lined up, because the distances traveled by planets with each revolution around the sun would be different.