farthest point

• apexUppermost point or culmination
• extremityOutermost part or limit
• horizonApparent earth-sky meeting
• distantFar away or aloof
• remoteDistant or controller

outpost · frontier · edge · boundary · limit · terminus · zenith · peak · outer · beyond · reach · utmost · ultimate · peripheral · far-flung · endpoint · verge · brink

• moon distanceapogee, perigee, lunar orbit, closest approach
• extremesbest, worst, biggest, smallest, highest
• outer edgesedge, border, boundary, perimeter, periphery