A story In modern long range navigation, the precise location and speed of moving craft are continuous ly moni tored and updated. A system of navi gat ion satellites cal led NAVSTAR permits locations and speeds anywhere on earth to be determined to within about 16m and 2cm/. However if relativity effects were not taken into account, speeds could not be determined any closer than about 20cm/s, which is unacceptable for modern navi gat ion systems. How can something as abstract as Einstain's relativity be invol ved in something as practical as navi gationIn modern long range navigation,the precise location and speed of moving craft are continuously monitored and updated.A system of navigation satellites called NAVSTAR permits locations and speeds anywhere on earth to be determined to within about 16m and 2cm/s.However if relativity effects were not taken into account,speeds could not be determined any closer than about 20cm/s,which is unacceptable for modern navigation systems.How can something as abstract as Einstain’s relativity be involved in something as practical as navigation?