system
Given the following post, respond as if you're commenting on Reddit:
human
Does the rate of gravity change from place to place? For example at higher altitudes does gravity get weaker?

And if it does, does NASA use a localized rate of gravity for their equations, or is the difference so negligible that it doesn’t matter?
gpt
Yes, slightly. 

There’s a common misconception that astronauts on the ISS experience no gravity. This isn’t true, they’re experiencing nearly the same as us, they “float” because they’re constantly falling back towards earth. 

Technically your head experiences a weaker gravity than your feet, so your feet age more slowly than your head. The closer you are to a massive object the more slowly time passes.