If black holes evaporate via Hawking radiation, a solar mass black hole will evaporate (beginning once the temperature of the cosmic microwave background drops below that of the black hole) over a period of 10 years. A supermassive black hole with a mass of 10 M ☉ will evaporate in around 2×10 years. Some monster black holes in the universe are predicted to continue to grow up to perhaps 10 M ☉ during the collapse of superclusters of galaxies. Even these would evaporate over a timescale of up to 10 years.