Editing Surface brightness (section)

{{Short description|Astronomical term for luminosity per area}}
In [[astronomy]], '''surface brightness''' (SB) quantifies the [[apparent brightness]] or [[spectral flux density|flux density]] per unit [[Solid angle|angular area]] of a spatially extended object such as a [[galaxy]] or [[nebula]], or of the [[night sky]] background.  An object's surface brightness depends on its surface luminosity density, i.e., its [[luminosity]] emitted per unit surface area. In [[Visible-light astronomy|visible]] and [[Infrared astronomy|infrared]] astronomy, surface brightness is often quoted on a [[Astronomical magnitude|magnitude]] scale, in '''magnitudes per square [[Minute and second of arc|arcsecond]]''' (MPSAS) in a particular [[Astronomical filter|filter band]] or [[photometric system]].

Measurement of the surface brightnesses of celestial objects is called surface [[Photometry (astronomy)|photometry]].