Luminosity distance

$M\; =\; m\; -\; 5\; (log\_\{10\}\{D\_L\}\; -\; 1)!,$

which gives:

$D\_L\; =\; 10^\{frac\{(m\; -\; M)\}\{5\}+1\}$

where D_L is measured in parsecs. For nearby objects (say, in the Milky Way) the luminosity distance gives a good approximation to the natural notion of distance in Euclidean space.

For distant objects far beyond the Milky Way, the relation is less clear, since the apparent magnitude is affected by spacetime curvature, redshift, and time dilation. Calculating the relation between the luminosity distance and, for example, redshift of an object requires taking all of these factors into account.

See also

• Distance measures (cosmology)
• distance modulus

External links

• Ned Wright's Javascript Cosmology Calculator
• iCosmos: Cosmology Calculator (With Graph Generation )