When Alan Bean was returning to Earth from a trip to the Moon, it seemed to him that the way back was shorter. Likewise, that is how you felt when you returned from a voyage, certainly not from the moon. This phenomenon is very widespread, which has prompted scientists to try to give an answer.
Initially, the experts highlighted the “return trip effect” which is related to familiarity with the road and facilities; when we return, we are more aware of the environment we are passing through, which affects the sense of time. However, such an effect was also observed in air travel, so there must be other reasons.
In fact, it is thought that the phenomenon is not related to the measurement of time, but to the judgment we make of it. When we leave for somewhere, we pay more attention to time (check the clock for example) which gives the feeling as if time is not moving.
Likewise, we are happier when we leave for the journey than when we return. Since we are excited, it seems like it takes a long time to get to the destination, whereas when we return, the circumstances are different.
Source: Bright Side