Would you like to know why mass doesn’t matter here? Or shoud we wrap up the conversation?

Sure, though I imagine it's just the size of the mass in relation to the absolute massive mass (ha pun) of Earth.

Yes.

~~The force of gravity is proportional to the mass of the earth plus the mass of the other object. however, when the mass the object is very small compared to the earth (which is true for both a feather and a spaceship), we just do the calculations for the movement of the feather or spaceship, and assume the earth stays in one place. Or in other words, whether its a feather or a spaceship, the total mass is essentially just the mass of the earth, so the calculations are the same for both objects.~~ EDIT: I got this wrong, sorry!

Another way to look at it is this: The

*force* of gravity pulling on a spaceship is much larger than the force on the feather, because the force is proportional to the mass. But the

*acceleration* on the feather is the same as that on the spaceship because acceleration = force / mass. So the mass cancels out.