Can a Laser Beam Move Faster Than Light Across the Moon's Surface?

[briteliner]

Homework Statement

You point a laser flashlight at the moon producing a spot of light on its surface. At what minimum angular speed must you sweep the laser beam in order for the light spot to streak across the moon's surface with speed v>c? Why can't you transmit information between research bases on the moon with the flying spot?

Homework Equations

The Attempt at a Solution

I figure I need to find an angle but I don't get how since there is not much info given in the problem

 

[Irid]

It's probably assumed you know the distance to the Moon d. Then just find the angular velocity for the spot to travel at the speed of light c.

 

[briteliner]

Ok so I get that w=csin(theta)/d but I still don't have an angle

 

[Irid]

You don't need any angle, just assume \theta = 90 deg for the greatest angular speed.

 

[briteliner]

But how can that be right? C/d just gives me .789 rad/s

 

[Irid]

awesome, right?