Spectrum of moon light

Posted by Marcel van der Steen in Explanation 51 Comments»

005_moonWhen I was looking for a spectrum of moonlight, I could not find it on the internet. As I do a lot of lamp measurements myself (see the category lamp measurements), I decided to measure the moon spectrum myself and put that info available on the internet.

Measurement circumstances

The measurement has been done on 14th of April 2014. It was an evening with few clouds and we had a full moon, well visible. Taking measurements with the spectrometer SpecBos 1211 can then be done in two ways.

1) measurement of the illuminance (in lux). However the expected illuminance is only 1 lux and that results in a very faint spectrum with signals for each wavelength too close to the noise limit to have a nice signal.

2) measurement of luminance (in Cd/mˆ2), and that requires a very well alignment of the measurement device in the direction of the moon, as the sensitivity area of the device in this mode is only two degrees wide.

I mounted the spectrometer on a tripod and kept on aligning and measuring until I had an output with a high signal.

Measurement results

Here the spectrum and derived parameters.




Lastly an csv-file with the measurement data, which is an average of 24 measurements.


Added per 20 June 2018:
And here the file extended with a column for Ee (in W/m^2/nm) and the approximated illuminance value (in lux). An illuminance value of 0.14 lux is what would be expected.

51 replies on “Spectrum of moon light”

The red:far red (R:FR) ratio of sunlight during the day is more than 1.2, while that of moonlight is between 0.18 and 0.22

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