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For example, a magnitude 2.0 star is 2.512 times as bright as a magnitude 3.0 star, 6.31 times as magnitude 4.0, and 100 times magnitude 7.0. The brightest astronomical objects have negative apparent magnitudes: for example, Venus at −4.2 or Sirius at −1.46.
Consequently, a magnitude 1 star is about 2.5 times brighter than a magnitude 2 star, about 2.5 2 times brighter than a magnitude 3 star, about 2.5 3 times brighter than a magnitude 4 star, and so on. This is the modern magnitude system, which measures the brightness, not the apparent size, of stars.
Normal maximum brightness is 2.29; magnitude 0.7 once observed 2.39 Epsilon Boötis: Binary star system 2.41 2.14 Mintaka: Triple star system 2.41 Kappa Scorpii: Binary star system Maximum brightness 2.42 2.31 Beta Pegasi: Star 2.42 Eta Ophiuchi: Binary star system 2.440 Phecda: Binary star system 2.45 2.38 Eta Canis Majoris: Star 2.46 Alpha ...
For example, Betelgeuse has the K-band apparent magnitude of −4.05. [5] Some stars, like Betelgeuse and Antares, are variable stars, changing their magnitude over days, months or years. In the table, the range of variation is indicated with the symbol "var". Single magnitude values quoted for variable stars come from a variety of sources.
To help compare different orders of magnitude, the following list describes various source in lux, ... 10 5: 100 kilolux 110 kilolux: Bright sunlight 120 kilolux:
[4] [5] Absolute magnitudes of stars generally range from approximately −10 to +20. The absolute magnitudes of galaxies can be much lower (brighter). For example, the giant elliptical galaxy M87 has an absolute magnitude of −22 (i.e. as bright as about
The apparent magnitude is the observed visible brightness from Earth which depends on the distance of the object. The absolute magnitude is the apparent magnitude at a distance of 10 pc (3.1 × 10 17 m), therefore the bolometric absolute magnitude is a logarithmic measure of the bolometric luminosity.
limiting magnitude with 12.5" reflector is 15; 6 Bright suburban sky 5.1–5.5 18.5–19.25 the zodiacal light is invisible; light pollution makes the sky within 35° of the horizon glow grayish white; clouds anywhere in the sky appear fairly bright; even high clouds (cirrus) appear brighter than the sky background; surroundings are easily visible