"First of all not all Astronomers believe that . All though it is a very long way to the closest star we really do n't know how far stars are away from us it is not possible to know . It is an educated guess at best ."
"It 's not tough , especially for close stars . http : //www.uwgb.edu/dutchs/CosmosNotes/distance.htm You use triangulation based on the orbit of the earth ."
"It is an educated guess at best ."
"It 's not tough , especially for close stars ."