Source: German Aerospace Center
In the field of archaeology the age of finds or the time of events can sometimes be determined relatively easily, for example via the number of tree rings or the rate of decomposition of radioactive elements. However, there is unfortunately no direct and absolute indicator for the age of the Universe. Astronomers have, however, found two ways to arrive at a good estimate.
Astronomers have ultimately calculated that the Universe is 13.7 billion years old. (read more)