::Apparent magnitude


Title::maximum    Apparent::visible    Stars::light    Simbad::scale    Author::nssdc    Objects::naked


Asteroid 65 Cybele and two stars, with their magnitudes labeled

The apparent magnitude (m) of a celestial object is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere. The brighter an object appears, the lower its magnitude value (i.e. inverse relation). In addition, the magnitude scale is logarithmic: a difference of one in magnitude corresponds to a change in brightness by a factor of about 2.5.

Generally, the visible spectrum (vmag) is used as a basis for the apparent magnitude. However, other spectra are also used (e.g. the near-infrared J-band). In the visible spectrum, Sirius is the brightest star after the Sun. In the near-infrared J-band, Betelgeuse is the brightest. The apparent magnitude of stars is measured with a bolometer.

Apparent magnitude sections
Intro   History    Calculations    Standard reference values   Table of notable celestial objects  See also  References   External links   

PREVIOUS: IntroNEXT: History