Abstract: Neutron stars are born extremely hot in the aftermath of a supernova and then cool by neutrino emission over the next million years. Measurements of the temperature of neutron stars of various ages provide crucial insights into nuclear physics that govern neutron star cooling, such as proton-neutron asymmetry, superfluidity, and transitions to hyperons and deconfined quarks at high densities. Here I provide an update on observations of the youngest neutron star known and its rapid cooling over 20 years and implications for neutron superfluidity and proton superconductivity.