How much ultraviolet light comes from the moon at night and from the Sun during the day? I am interested in using a UV camera on a robot to see the UV from the sun/moon to do robot localization.

  • $\begingroup$ "How much" is rather ambiguous. Do you have a wavelength range you're interested in? Are you looking for a $W m^{-2}$ type answer? Even still, this will be highly variable depending on physical location on Earth, weather, altitude, time of day, etc. I think you need to provide more specific parameters concerning what it is you want or you're trying to do. $\endgroup$
    – zephyr
    Apr 27, 2017 at 19:52

1 Answer 1


"A little" (compared to how much visible light there is)

enter image description here (from a question on physics se

The sun produces relatively little UV radiation, most of its light is visible, or infrared, and anything shorter than about 290nm is completely blocked by the atmosphere (remember to thank the atmosphere today)

UVa (in the range 400-320) and UVb (320-290nm) do get through. The sun is so very bright, that it is by far the brightest natural source of UV on the Earth.

The moon is about 400,000 times dimmer than the sun. Ultraviolet reflected off the moon could reach the Earth. It would be very dim.

At night UV camera systems use active illumination rather than depending on the moon.


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