This is a list of stars arranged by their apparent magnitude – their brightness as observed from Earth. It includes all stars brighter than magnitude +2.50 in visible light, measured using a V-band filter in the UBV photometric system. Stars in binary systems (or other multiples) are listed by their total or combined brightness if they appear as a single star to the naked eye, or listed separately if they do not. As with all magnitude systems in astronomy, the scale is logarithmic and inverted i.e. lower/more negative numbers are brighter. Most stars on this list appear bright from Earth because they are nearby, not because they are intrinsically luminous. For a list which compensates for the distances, converting the apparent magnitude to the absolute magnitude, see the list of most luminous stars. Measurement The Sun is the brightest star as viewed from Earth, at −26.74 mag. The second brightest is Sirius at −1.46 mag. For comparison, the brightest non-stellar objects in the Solar System have maximum brightnesses of: the Moon −12.7 mag, Venus −4.89 mag, Jupiter −2.94 mag, Mars −2.91 mag, Mercury −2.45 mag, and Saturn −0.49 mag. Any exact order of the visual brightness of stars is not perfectly defined for four reasons: Stellar brightness is based on the apparent visual magnitude as perceived by the human eye, from the brightest stars of 1st magnitude to the faintest at 6th magnitude. Since the invention of the optical telescope and the documenting of binary stars and multiple star systems, stellar brightness could be expressed as either individual (separate) or total (combined) magnitude. The table is ordered by combined magnitude of all naked eye components appearing as if it they were single stars. Such multiple star systems are indicated by parentheses showing the individual magnitudes of component stars bright enough to make a detectable contribution. For example, the binary star system Alpha Centauri has the total or combined magnitude of −0.27, while its two component stars have magnitudes of +0.01 and +1.33. New or more accurate photometry, standard filters, or adopting differing methods using standard stars can measure stellar magnitudes slightly differently. This may change the apparent order of lists of bright stars. The table shows measured V magnitudes, which use a specific filter that closely approximates human vision. However, other kinds of magnitude systems do exist based on different wavelengths, some well away from the distribution of the visible