Glow-in-the-dark tattoos only appear under UV light. They use ink containing a fluorescent dye.
[📹 Iro Tattoo / https://t.co/1moE8bX2jL]
https://t.co/r5KY8S600g
In 1985 an astronaut noticed this physical behavior of a handle, that turned out to be the proof of a theorem: the tennis racket theorem (also dubbed the Dzhanibekov effect)
Tumbleweeds start out as tiny seedlings; by summer the plant has a round shape. They grow flowers and fruits. By fall they dry and detach from their roots, so they spread their seeds.