One would usually refer to this object as a 'moon' or 'satellite'.
round characters are those ones who give u the complete image of the person,profounded and threedimensional I dont think that is the correct definition. A round character is a major character in a work of fiction who encounters conflict and who is changed by it.
An object or picture can be made round. It can be done in picture tools after selecting it.
A cylinder is a long round object with flat circular ends.
A round object with flat, circular ends is a cylinder. It is shaped like a can of vegetables.
scrawl rhymes with "ball" which is a round object used in games!