I think this question depends on your expectations of up and down.
If you're only thinking in terms of reference frames, it could be whatever you want. Though conventionally, down would be towards Earth.
In terms of acceleration and feeling a force applied to you, there are 3 scenarios I can see. We will define the direction of acceleration as "down"
Acceleration toward earth if you are entering orbit at less than terminal velocity. In this case is towards earth
No acceleration towards earth if you are entering at terminal velocity. In this case there is no down.
Decceleration towards earth if you are entering faster than terminal velocity. In this case down is towards where you came from.
I would argue that case 2 only exists at 1 point in the atmosphere as terminal velocity will be gradient with the density of atmosphere. In this case (2) down would be towards earth, towards space, and undefined depending on your distance from the surface.
Fluffbutt69 t1_j5wyn46 wrote
Reply to If you were in space facing Antartica and you flew towards it, gravity-wise would you be going up or down? by lifesyndrome
I think this question depends on your expectations of up and down.
If you're only thinking in terms of reference frames, it could be whatever you want. Though conventionally, down would be towards Earth.
In terms of acceleration and feeling a force applied to you, there are 3 scenarios I can see. We will define the direction of acceleration as "down"
Acceleration toward earth if you are entering orbit at less than terminal velocity. In this case is towards earth
No acceleration towards earth if you are entering at terminal velocity. In this case there is no down.
Decceleration towards earth if you are entering faster than terminal velocity. In this case down is towards where you came from.
I would argue that case 2 only exists at 1 point in the atmosphere as terminal velocity will be gradient with the density of atmosphere. In this case (2) down would be towards earth, towards space, and undefined depending on your distance from the surface.