Next question, what is the smallest object whose gravitational field could reliably be measured by the accelerometer in your phone? We know that it can measure

Next question, what is the smallest object whose gravitational field could reliably be measured by the accelerometer in your phone? We know that it can measure the field of the Earth at more or less sea level, how much less heavy/further away could something get for your phone to feel it? my attempt: diameter of earth = 12742 km sea level = distance from earth = 12742/2 weight of empire state building = 331000000 kg resolution of BMA280 in the iPhone 6: 1/4096 g mass of earth = 5.972e+24 kg gravity of earth = 1 g km to m = 1000x (12742/2. * sqrt(331000000 / (5.972e+24 / 4096.))) * 1000 = 3 meters So your phone should be able to register 1 bit of resolution when the empire state building is 3 meters away or less, otherwise it would be too far away to detect. Of course the empire state building would need to be compressed into a single point but that's a minor practical concern.