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  2. Absolute magnitude - Wikipedia

    en.wikipedia.org/wiki/Absolute_magnitude

    For example, the giant elliptical galaxy M87 has an absolute magnitude of −22 (i.e. as bright as about 60,000 stars of magnitude −10). Some active galactic nuclei ( quasars like CTA-102 ) can reach absolute magnitudes in excess of −32, making them the most luminous persistent objects in the observable universe, although these objects can ...

  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

    The faintest stars visible with the naked eye on the darkest night have apparent magnitudes of about +6.5, though this varies depending on a person's eyesight and with altitude and atmospheric conditions. [2] The apparent magnitudes of known objects range from the Sun at −26.832 to objects in deep Hubble Space Telescope images of magnitude ...

  5. Luminosity - Wikipedia

    en.wikipedia.org/wiki/Luminosity

    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.

  6. Orders of magnitude (illuminance) - Wikipedia

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

    2.5 decilux: Full Moon on a clear ... 10 5: 100 kilolux 110 kilolux: Bright sunlight ... measured in candelas per square metre and grouped by order of magnitude ...

  7. Phase curve (astronomy) - Wikipedia

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

    In astronomy, a phase curve describes the brightness of a reflecting body as a function of its phase angle (the arc subtended by the observer and the Sun as measured at the body). The brightness usually refers the object's absolute magnitude, which, in turn, is its apparent magnitude at a distance of one astronomical unit from the Earth and Sun.

  8. Bortle scale - Wikipedia

    en.wikipedia.org/wiki/Bortle_scale

    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

  9. Distance modulus - Wikipedia

    en.wikipedia.org/wiki/Distance_modulus

    Distance moduli are most commonly used when expressing the distance to other galaxies in the relatively nearby universe.For example, the Large Magellanic Cloud (LMC) is at a distance modulus of 18.5, [2] the Andromeda Galaxy's distance modulus is 24.4, [3] and the galaxy NGC 4548 in the Virgo Cluster has a DM of 31.0. [4]