It's a sad time for the astrophysics world. Vera Rubin, who was instrumental to confirming the existence of dark matter, has died of dementia at the age of 88. While the concept of dark matter had been proposed by Fritz Zwicky back in 1933, it was Rubin and her colleague Kent Ford who provided firm evidence in the 1960s and 1970s. They noticed that the stars at the outside of spiral galaxies spin just as quickly as those on the inside -- according to the understanding of gravity at the time, these enormous star formations should tear themselves apart. The only viable explanation was an invisible mass, roughly 10 times larger than what we can see, that was holding everything together.