I talked to the guy that developed the LaTex plugin for the equation editing bug at the bottom of each page. Hopefully resolved soon.

Do the math – if a star emits photons that reach my eye and my pupil has a surface area of Xmm^2 and the distance is Y light years and the photon stream is X/second, how many photons is that per second to emit across the entire sphere *at that distance*? That equates to how many atoms dropping energy levels how often and how many atoms are in a star?