▁equ ino x ▁in ▁U T ▁always ▁falling ▁either ▁on ▁ 2 0 ▁or ▁ 2 1 ▁March ▁in ▁the ▁period ▁of ▁ 1 7 9 7 ▁to ▁ 2 0 4 3 , ▁falling ▁on ▁ 1 9 ▁March ▁in ▁ 1 7 9 6 ▁the ▁last ▁time ▁and ▁in ▁ 2 0 4 4 ▁the ▁next . ▁Ex cept ▁for ▁ 2 0 0 3 ▁and ▁ 2 0 0 7 , ▁the ▁v ernal ▁equ ino x ▁has ▁started ▁on ▁ 2 0 ▁March ▁since ▁ 1 9 8 0 , ▁and ▁is ▁project ed ▁to ▁until ▁ 2 0 4 3 . ▁ ▁Because ▁the ▁Earth ' s ▁axis ▁is ▁at ▁an ▁angle , ▁some ▁signs ▁take ▁longer ▁to ▁rise ▁than ▁others , ▁and ▁the ▁farther ▁away ▁from ▁the ▁equ ator ▁the ▁observer ▁is ▁situated , ▁the ▁greater ▁the ▁difference . ▁Thus , ▁signs ▁are ▁spoken ▁of ▁as ▁" long " ▁or ▁" short " ▁asc ension . ▁ ▁Pre cess ion ▁of ▁the ▁equ ino xes ▁▁ ▁The ▁z od iac ▁system ▁was ▁developed ▁in ▁Bab yl onia , ▁some ▁ 2 , 5 0 0 ▁years ▁ago , ▁during ▁the ▁" Age ▁of ▁A ries ". ▁At ▁the ▁time , ▁it ▁is ▁assumed , ▁the ▁pre cess ion ▁of ▁the ▁equ ino xes ▁was ▁unknown . ▁Contempor ary ▁use ▁of ▁the ▁coordinate ▁system ▁is ▁presented ▁with ▁the ▁choice ▁of ▁interpre ting ▁the ▁system ▁either ▁as ▁sid ere al , ▁with ▁the ▁signs ▁fixed ▁to ▁the ▁stell ar