Yes, quite right. Although it would be preferable as 4π steradians as that is the SI unit of solid angle. http://en.wikipedia.org/wiki/Solid_angle http://en.wik

Yes, quite right. Although it would be preferable as 4π steradians as that is the SI unit of solid angle. http://en.wikipedia.org/wiki/Solid_angle http://en.wikipedia.org/wiki/Solid_angle