[APML]: Surface brightness of extended objects

[Jerry Lodriguss <jml@astropix.com>]

Ok, here we go: <G>

If you move closer to an extended deep-sky object, does the surface
brightness get any brighter?

Consider 5 classes of objects, stars, star clusters, galaxies, planetaries
and nebulae.

Take a one square degree nebula at 2 light years distance. You move twice
as close, to one light year. Now the nebula takes up four times the area of
the sky, so it's 2 x 2 degrees = 4 square degrees.

Is it any brighter per unit of surface brightness?

Jerry