Magnitude

    The brightness of astronomical objects is measured in magnitude. The brightest objects have the lowest numbers while the dimmest objects have the highest numbers. The following table was taken from http://en.wikipedia.org/wiki/Apparent_magnitude

Magnitude  

Celestial object

−26.73

Sun

−12.6

full Moon

−8.0

Maximum brightness of an Iridium Flare

−4.4

Maximum brightness of Venus

−4.0

Faintest objects observable during the day with naked eye

−2.8

Maximum brightness of Mars

−1.5

Brightest star (except for the sun) at visible wavelengths: Sirius

−0.7

Second brightest star: Canopus

0

The zero point by definition: This used to be Vega

3

Faintest stars visible in an urban neighborhood

6

Faintest stars observable with naked eye

12.6

Brightest quasar

27

Faintest objects observable in visible light with 8m ground-based telescopes

30

Faintest objects observable in visible light with Hubble Space Telescope

38

Faintest objects observable in visible light with planned OWL (2020)