[z2h-a6n]

Not to nitpick (I only stumbled upon this recently myself), but the mechanism driving a Crookes radiometer (which I presume is the type you're talking about) is not photon pressure, but interactions with the low pressure gas in the bulb [1].

[1]: https://en.wikipedia.org/wiki/Crookes_radiometer#Explanation...

[jjtheblunt]

Yes(!): the explanation on the little paper that came with it explained such.