This year, October 31 was more than just Halloween. It was also the first global celebration of Dark Matter Day. In 25 countries, 11 US states and online, people interacted with scientists, watched demonstrations, viewed films, took in art exhibits and toured laboratories to learn about the ongoing search for dark matter.
Symmetry has collected a series of photos from participants around the world. Check out how people celebrated Dark Matter Day and download a commemorative dark matter poster (to be printed using visible matter).