50 Years of Human Space Exploration. This is by far the coolest pin I will see tonight. So amazing as to how far the space exploration campaign(s) has come since we first step foot into the putter abyss!
PHD Comics: Gravitational Waves Explained Simple explanation but really interesting for further understanding on gravitational waves. "That's one small step for man, one giant leap for mankind" Neil Armstrong quote Mehr
Phylogenetic Tree of Life -The OpenLearn site used to offer this phylogenetic chart in the shape of a tree as a free poster, but no more. They do have an online version of this same illustration, expandable and with links and an explanatory guide.