[SOLVED] synchronous orbit 1. The problem statement, all variables and given/known data A orbiting satellite stays over a certain spot on the equator of (rotating) Mercury. What is the altitude of the orbit (called a "synchronous orbit")? The answer needs to be in km. 2. Relevant equations I know the synchronous orbit is where the satellite has a period equal to the average roational period of the planet. T^2 = ((4pi^2)/(GM))r^3 T would be the rotational period of Mercury. G is the gravitational constant. M would be mercury's mass. I would be solving for r. 3. The attempt at a solution So far i have been plugging in numbers but nothing has been working. Should T be in years, days, hours, or seconds?