# Speed of moon orbiter around the moon?

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During the Apollo moon landings how was the lunar lander able to slow down enough to land on the moon? And then speed up enough to connect back up to the orbiter? Let alone getting into the same orbit. All movies show this in slow motion and makes it look easy.

In: Planetary Science

Every celestial body (Earth, moon, sun, etc) has a “sphere of influence” where the gravity from that celestial body dominates. So for example, for us on Earth, we’re still affected by the sun’s gravity, but the effect of Earth’s gravity is so much bigger than the sun’s that the vast majority of the time we basically ignore the sun’s gravity.

So when the lander is near the moon, it really only needs to account for the effect of the moon’s gravity. The moon has significantly less gravity than the Earth, so it’s much easier to take off from and land on than it would be on Earth. Similarly, orbits around the moon are much slower than they are on Earth.

As to how they were able to link up after leaving the moon, it’s just timing and math. If you know the shape of your orbit and the speed of your orbit, you can time how long it takes object A to reach a point, and for object B to reach that same point. Sync up those times and you’ve made a rendezvous