WTF date

benaryorg@gnutoo ~ $ date --date=+@9999999999999999999999999
date: invalid date ‘+@9999999999999999999999999’
benaryorg@gnutoo ~ $ date --date=+@999999999999999999999999
date: invalid date ‘+@999999999999999999999999’
benaryorg@gnutoo ~ $ date --date=+@99999999999999999999999
date: invalid date ‘+@99999999999999999999999’
benaryorg@gnutoo ~ $ date --date=+@9999999999999999999999
date: invalid date ‘+@9999999999999999999999’
benaryorg@gnutoo ~ $ date --date=+@999999999999999999999
date: invalid date ‘+@999999999999999999999’
benaryorg@gnutoo ~ $ date --date=+@99999999999999999999
date: invalid date ‘+@99999999999999999999’
benaryorg@gnutoo ~ $ date --date=+@9999999999999999999
date: invalid date ‘+@9999999999999999999’
benaryorg@gnutoo ~ $ date --date=+@999999999999999999
date: time 999999999999999999 is out of range
benaryorg@gnutoo ~ $ date --date=+@99999999999999999
date: time 99999999999999999 is out of range
benaryorg@gnutoo ~ $ date --date=+@9999999999999999
Sat Jan 25 18:46:39 CET 316889355
benaryorg@gnutoo ~ $