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  2. Solar luminosity - Wikipedia

    en.wikipedia.org/wiki/Solar_luminosity

    The Sun is a weakly variable star, and its actual luminosity therefore fluctuates. [3] The major fluctuation is the eleven-year solar cycle (sunspot cycle) that causes a quasi-periodic variation of about ±0.1%. Other variations over the last 200–300 years are thought to be much smaller than this. [4]

  3. Luminosity - Wikipedia

    en.wikipedia.org/wiki/Luminosity

    For example, consider a 10 W transmitter at a distance of 1 million metres, radiating over a bandwidth of 1 MHz. By the time that power has reached the observer, the power is spread over the surface of a sphere with area 4πr 2 or about 1.26×10 13 m 2, so its flux density is 10 / 10 6 / (1.26×10 13) W m −2 Hz −1 = 8×10 7 Jy.

  4. Sky brightness - Wikipedia

    en.wikipedia.org/wiki/Sky_brightness

    (The S 10 unit is defined as the surface brightness of a star whose V-magnitude is 10 and whose light is smeared over one square degree, or 27.78 mag arcsec −2.) The total sky brightness in zenith is therefore ~220 S 10 or 21.9 mag/arcsec² in the V-band.

  5. Sun - Wikipedia

    en.wikipedia.org/wiki/Sun

    Because energy transport in the Sun is a process that involves photons in thermodynamic equilibrium with matter, the time scale of energy transport in the Sun is longer, on the order of 30,000,000 years. This is the time it would take the Sun to return to a stable state if the rate of energy generation in its core were suddenly changed. [106]

  6. Orders of magnitude (illuminance) - Wikipedia

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

    Bright sunlight 120 kilolux: Brightest sunlight Luminance. This section lists examples of luminances, measured in candelas per square metre and grouped by order of ...

  7. The sun is now in its solar maximum, meaning more aurora activity

    www.aol.com/news/sun-now-solar-maximum-meaning...

    Scientists said the sun is now in its solar maximum, or the peak of its 11-year solar cycle. The sun is now in its solar maximum, meaning more aurora activity Skip to main content

  8. The Sun: study shows it's less active than sibling stars ...

    www.aol.com/news/sun-study-shows-less-active...

    Has the Sun entered a stage of old age? For premium support please call: 800-290-4726 more ways to reach us

  9. Absolute magnitude - Wikipedia

    en.wikipedia.org/wiki/Absolute_magnitude

    At that time, its absolute magnitude had decreased to =, [42] and it was realised that the 1819 apparition coincided with an outburst. 289P/Blanpain reached naked eye brightness (5–8 mag) in 1819, even though it is the comet with the smallest nucleus that has ever been physically characterised, and usually doesn't become brighter than 18 mag ...