What is the temperature inside a black hole?
This is actually quite a complex question. A simple answer is extremely cold; only slightly higher than absolute zero (0K, -273.15 Celsius, -459.67 Fahrenheit), which is theoretically the coldest anything can be. Astronomers say that black holes emit “black body radiation”, which means that they are not hot enough to emit radiation that we can see with our eyes (like stars can). Black body radiation produced by black holes is called Hawking radiation (named after the scientist Stephen Hawking)
However, An actual temperature of a black hole depends on the size of the black hole and the relationship between mass of the black hole and temperature is inversely proportional (T = 0.00000006M; where T = temperature and M = mass), meaning the bigger the black hole, the colder it is. Now for the tricky bit: black holes do emit radiation (albeit a small amount of Hawking radiation) and anything emitting radiation looses mass (because it is loosing photons, which have a teeny tiny amount of mass). So, as the black hole emits radiation (and looses mass) over time, it heats up. Eventually, if nothing new “falls into” in the black hole, it will become so small and so hot that it will probably disappear, but nobody really knows (the process of decreasing mass by Hawking radiation is unfathomably slow).
