 White dwarfs are slowly cooling stars which have cast off their outer layers during the last stages of their fusion burning phase. Roughly 98% of all the stars in the universe will ultimately end up as white dwarfs, including our own sun. To investigate the physics underpinning white dwarf evolution, astronomers compared cooling white dwarfs into massive collections of stars. The globular clusters M3 with roughly half a million stars and M13 with several hundred thousand stars. Interestingly, their star populations which will eventually give rise to white dwarfs are different. In particular, the overall color of stars at the end of their red giant phase are bluer in M13 and blue stars are hotter because they are burning hydrogen on their surfaces. This slows down their cooling rate. The evolution of white dwarfs has previously been modeled as a predictable cooling process leaving astronomers use them as a natural clock to determine the age of star clusters. However, white dwarfs burning hydrogen could cause these age estimates to be inaccurate by as much as a billion years.