Tootfinder

More demonstration spectroscopy at the first #Geistesblitz in #Bochum - a blue card also reflecting much NIR while a black flyer (of ESA's #ESERO education program to which this belongs) absorbing it.

The sky over #Bochum at the end of the first #Geistesblitz on Friday: Saturn shining through the shaft tower on top of the Deutsches #Bergbaumuseum with the full moon looking on.