After watching Interstellar, I realized something different from my current known fact.

In the movie Interstellar, as you get closer to the black hole or Miller's planet, which has a great amount of mass/gravitational force your time will move slower relatively to the people outside this zone, vice versa.

That means if you close to heavy mass object you will perceive normal time but when you observe people outside the zone you will see that they age faster, vice versa.

But how the fuck astronaut in space age slower? Shouldn't they age faster because they are slightly far away from the gravitational core (Earth) compare to people on earth?

Am I missing something?