How long does it take a black hole to vanish? In the 1970s, Stephen Hawking showed that black holes slowly lose mass through a quantum process now called Hawking radiation. You use a set of equations to calculate key properties of black holes at different scales. These range from tiny quantum black holes to supermassive ones. For each mass, you compute: - event horizon radius - radiation temperature - luminosity (energy output) - lifetime Then you predict which black holes from the Big Bang would be evaporating right now. Calculate what the final few thousand years look like. The remaining mass shrinks and the temperature soars. Compare that brightness to the Sun and search for real sky phenomena that might match.