If the object should not cast any shadows regardless of the light source then you can just turn "Cast shadows" off under the Render Stats of the object. If it should cast shadows from other light sources, then go to Window->Relationship Editors->Light Linking->Light-Centric, select the sphereLight on the left and deselect the object on the right.
Edit: Depending on the geometry of the object, you may get away by turning "Double Sided" off under Render Stats for the object.
Earth: The crazy asylum of the universe.
Last edited by PixalZA; 19-05-2014 at 04:20 PM.