How could a light source like the sun be approximated on Earth for testing, given how much brighter it is in space than anything else?

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    $\begingroup$ I would recommend reading Wikipedia about the units Lux, Lumen and Candela. Powerful lamps may exceed the Lux number of the Sun when illuminating a very small area. $\endgroup$
    – Uwe
    Commented Feb 5, 2019 at 12:42
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    $\begingroup$ A modern lighting of an operating theatre (160000 Lux) is even brighter than sunlight at a clear sky with the Sun at the zenith (130000 Lux). $\endgroup$
    – Uwe
    Commented Feb 5, 2019 at 23:06
  • $\begingroup$ Would you please remove or correct this wrong sentence: "This is also with consideration to the fact that no lamp can match the lux count of the sun." $\endgroup$
    – Uwe
    Commented Feb 6, 2019 at 16:27
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    $\begingroup$ @Uwe done. sentence removed $\endgroup$
    – jos
    Commented Feb 7, 2019 at 13:04

1 Answer 1


You can match the lux count of the sun, in a small area. The amount of solar power that shines on a satellite is about 1300 W/m2 in Earth orbit.

This is done at e.g. the ESA Large Space Simulator at ESTEC, in the Netherlands.

This provides a horizontal solar beam of 6-m diameter with excellent uniformity and very high long- and short-term stability (less than 0.5%). An intensity level of one solar constant (the standard solar energy received at Earth distance from the Sun, equivalent to 1380 watts per square metres) can be produced by operating 12 of 19 xenon lamp modules at a nominal power of 20 kilowatts per lamp. With all lamps at full power, engineers can achieve flux in excess of 2700 watts per square metre.

  • $\begingroup$ smaller versions are available $\endgroup$
    – user20636
    Commented Feb 5, 2019 at 13:35
  • $\begingroup$ larger one too (sort-of) ~350 kW on a 20x20cm area chemistry.stackexchange.com/q/71172/16035 $\endgroup$
    – uhoh
    Commented Feb 5, 2019 at 14:21
  • $\begingroup$ 20 kw lamps! NICE! $\endgroup$
    – Fattie
    Commented Feb 6, 2019 at 12:50

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