An experiment which reveals verification of the prediction of time dilation by special relativity. Muons, that are short-lived subatomic particles, are generated with vast energy in the upper atmosphere through the interaction of energetic cosmic rays. Muons contains a very short halflife in their own reference frame, approximately 2.2 us. As they are travelling very close to c, but, time dilation effects must become important. A naive calculation would mentioned that, without special relativistic effects, the muons would travel onto the average only approximate 700 m before decaying, never attaining the surface of the Earth. However Observations reveal that important numbers of muons do attain the Earth. The explanation is that muon is in moving frame of reference, and therefore time is slowed down for the muons relative to the Earth, extending effectively the halflife of the muons relative to the Earth, letting some of them to reach the surface.