2011-01-15, 10:34 AM
Tay Wrote:Why are we assuming its a sphere
Welcome to physics.It's an Indisputable fact that EVERYTHING is a sphere. Even you.
Seriously though, Its probably not assuming- its that the light that reaches our telescopes is all travelling at the same speed- so we can tell roughly how far away it came from, and conveniently the light reaching at any given point in time will be from the same distance away (if you can filter out light from other sources anyway), thus the edge of what we can see is always going to be roughly spherical