http://www.falstad.com/gravity.html

> Physics 324 - Modern Physics for Engineers

> "A body is at rest tends to stay at rest, plus there's no gravity"

> "The gravity of the moon can be said to be negligible, and also the moon's a vacuum, there is no external force on the pen. Therefore it will float where it is."

> "The pen will float away because the gravitational pull of the moon, being approximately 1/6 that of the earth, will not be enough to cause the pen to fall nor remain stationary where it is. The gravatational pull of other objects would influence the pen"