Centauro event

A Centauro event is a kind of anomalous event observed in cosmic-ray detectors since 1972. They are so named because their shape resembles that of a centaur: i.e., highly asymmetric.

If some versions of string theory are correct, then high-energy cosmic rays could create black holes when they collide with molecules in the Earth's atmosphere. These black holes would be tiny, with a mass of around 10 micrograms. They would also be unstable enough to explode in a burst of particles within around 10 seconds.