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  2. List of brightest stars - Wikipedia

    en.wikipedia.org/wiki/List_of_brightest_stars

    Star Distance (ly) Spectral type Notes Milky Way –26.74 Sun 0 G2V Large Magellanic Cloud: 8.99 – 9.22 (variable) [10] HD 33579: 163,000 A3Ia + The Luminous Blue Variables S Doradus and R71 are brighter during their outbursts. Small Magellanic Cloud: 10.47 [11] SK 69: 200,000 B8Ia Andromeda Galaxy: 15.6 [12] [DMM2009] J004406.32+420131: ...

  3. Magnitude (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Magnitude_(astronomy)

    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.

  4. Apparent magnitude - Wikipedia

    en.wikipedia.org/wiki/Apparent_magnitude

    minimum brightness [42] +1.33: star Alpha Centauri B: seen from Earth +1.86: planet Mars: seen from Earth minimum brightness [42] +1.98: star Polaris: seen from Earth mean brightness [49] +3.03: supernova SN 1987A: seen from Earth in the Large Magellanic Cloud (160,000 light-years away) +3 to +4: Faintest stars visible in an urban neighborhood ...

  5. Zeta Eridani - Wikipedia

    en.wikipedia.org/wiki/Zeta_Eridani

    ζ Eridani (Latinised to Zeta Eridani) is the binary star's Bayer designation.WDS J03158-0849 A is its designation in the Washington Double Star Catalog.The designations of the two components as WDS J03158-0849 Aa and Ab derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).

  6. Bortle scale - Wikipedia

    en.wikipedia.org/wiki/Bortle_scale

    The Bortle dark-sky scale (usually referred to as simply the Bortle scale) is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution .

  7. Orders of magnitude (illuminance) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude...

    10 −5: 10 −4: 10 −3: mcd/m 2: 100 μcd/m 2: Cloudy night sky without moon [4] 400 μcd/m 2 "Darkest sky" [5] 1 mcd/m 2: Night sky [6] 1.4 mcd/m 2: Typical photographic scene lit by full moon [7] 10 −2: 5 mcd/m 2: Approximate scotopic/mesopic threshold [8] 10 −1: 10 0: cd/m 2: 2 cd/m 2: Floodlit buildings, monuments, and fountains [9 ...

  8. Cosmic distance ladder - Wikipedia

    en.wikipedia.org/wiki/Cosmic_distance_ladder

    By measuring these properties from a star's spectrum, the position of a main sequence star on the H–R diagram can be determined, and thereby the star's absolute magnitude estimated. A comparison of this value with the apparent magnitude allows the approximate distance to be determined, after correcting for interstellar extinction of the ...

  9. Photometry (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Photometry_(astronomy)

    An object's surface brightness is its brightness per unit solid angle as seen in projection on the sky, and measurement of surface brightness is known as surface photometry. [9] A common application would be measurement of a galaxy's surface brightness profile, meaning its surface brightness as a function of distance from the galaxy's center.