Why do certain objects in space orbit others?

[accelerate23]

Is it because of their different masses?

 

[Chronos]

It's all about mass. Actually, both bodies orbit each other, just that the more massive body is closer to the center of mass of the system so its motion is less affected than the lesser mass body.

 

[Drakkith]

See here: http://en.wikipedia.org/wiki/Barycenter

 

[accelerate23]

thanks :)