Back in 1995, when we were having our first astronaut on Mir
program, the cosmonauts were being interviewed and were
genuinely surprised that Americans did not celebrate Cosmonaut's
Day (April 12) like they did.

I know there is a Space Day/Week around July 20 (for the first manned
Moon landing with Apollo 11 in 1969), but I think the concept should
be turned into a full-blown holiday event, to wake people up to the
fact that we have actually left this planet - no mean feat, a major
milestone in our development, and something that no other species
on this planet has done, at least not by themselves.