 In the Star Fleet Universe, the Milky Way Galaxy is divided up into 24 sectors, each named for the letters of the Greek alphabet.Each sector extends from the galactic rim, and inwards to where star density and radiation problems cause ion storms, precluding travel.There are five 'void' sectors (Epsilon, Iota, Pi, Upsilon and Omega), where star and planet density is low, and which tend to generate large ion storms and radiation clouds, restricting travel from one set of sectors to another.