A black hole can have a temperature

Classical gravity gives a black hole an event horizon from which light does not return. Quantum field theory complicates that perfect darkness: Stephen Hawking calculated that a black hole should emit thermal radiation and lose energy. Temperature therefore belongs to an object famous for swallowing everything, linking gravity to thermodynamics in an unexpectedly literal way.

Hawking radiation has not been directly detected from an astrophysical black hole; for large black holes it would be extraordinarily faint. The claim is a robust theoretical prediction, not an observed glow. Its importance lies partly in the collision it creates: a horizon that hides information now also evaporates, leaving physics to explain what happens to that information.