So I'm teaching myself physics, and using Kerbal as a fun tool to help me do that. I'm running into some confusing Kerbal measurements that don't add up in my physics calculations. T2 = 4À2(Semi-Major Axis)3 / (GMKerbin ) Semi Major Axis = 12.7 million Meters (Apoapsis at the moon's radius, Periapsis about 100km above Kerbin's surface) When I put the above into the formula, I calculate an orbital period around 155,000 seconds. However, when I actually fly this in Kerbal I get an orbital period around 189,000 seconds. Big Difference. Does anybody here know why? Thank you!