Absolute Magnitude Luminates Absolutely

This week I want to discuss “What might cause the closer of two identical stars to appear dimmer than the farther one?”

Apparent Magnitude: A measurement of the brightness of stars without regard to their distance from Earth.

  • The scale in use today starts with the star Vega and an apparent magnitude of 0.0
  • Objects brighter than Vega are assigned negative numbers.  For example. Sirius, the night’s brightest star, has an apparent magnitude of -1.44
  • The scale was extended to include the dimmest stars visible through binoculars and telescopes.  For example, a pair of binoculars can see stars with an apparent magnitude of +10

Ignoring distance for a moment, all other things being equal, the closer of two identical stars will appear brighter (have a smaller apparent magnitude) to us than the more distant star.  When we account for the difference in distance, we use either or two measurements:  absolute magnitude and luminosity.

Absolute Magnitude: The brightness a star would have at a distance of ten parsecs (10 pc) or 32.6 ly. Continue reading “Absolute Magnitude Luminates Absolutely”