Re: can you see rainbows at night?

Hello Sian

What you are describing is a called lunar rainbow.  Rainbows are caused by 
suspended water droplets refracting light.  The light source is typically 
the sun, but occasionally a very bright moon will suffice. A very good 
description of the science involved in the causation and formation of 
rainbows can be found at the following web site:
 http://www.unidata.ucar.edu/staff/blynds/rnbw.html 

I hope this is helpful.
Greg