Among many stars in the Voynich manuscript there is an odd spiky symbol that resembles one found in early 13th century copy of Hildegard von Bingen's Liber Scivias.
Similarity is probably coincidental, but just for fun I'll speculate that the VMs spiky star represents thunder. Let's see what's around it.
The drawing may represent the fact that the light reaches the person before the sound.
What could the cross-shaped device producing thunder and lightning be? Maybe a cannon?
To quote Roger Bacon's description of gunpowder (yes, that Bacon):
"From the violence of that salt called saltpetre so horrible a sound is made
by the bursting of a thing so small, no more than a bit of parchment , that we find [the ear assaulted by a noise] exceeding
the roar of strong thunder, and a flash brighter than the most brilliant