▁Tru j illo ▁works ▁with ▁computer ▁software ▁and ▁has ▁exam ined ▁the ▁or bits ▁of ▁the ▁numerous ▁trans - Ne pt un ian ▁objects ▁( T NO s ), ▁which ▁is ▁the ▁outer ▁area ▁of ▁the ▁Sol ar ▁System ▁that ▁he ▁special ized ▁in . ▁In ▁late ▁August ▁ 2 0 0 5 , ▁it ▁was ▁announced ▁that ▁Tru j illo , ▁along ▁with ▁Michael ▁Brown ▁and ▁David ▁Rab in ow itz , ▁had ▁discovered ▁Er is ▁in ▁ 2 0 0 3 . ▁As ▁a ▁result ▁of ▁the ▁discovery ▁of ▁the ▁satellite ▁D ys nom ia , ▁Er is ▁was ▁the ▁first ▁T NO ▁known ▁to ▁be ▁more ▁massive ▁than ▁Pl uto . ▁ ▁Career ▁▁ ▁Tru j illo ▁attended ▁Oak ▁Park ▁and ▁River ▁Forest ▁High ▁School ▁in ▁Oak ▁Park , ▁Illinois . ▁ ▁He ▁received ▁his ▁B . Sc . ▁in ▁physics ▁from ▁the ▁Massachusetts ▁Institute ▁of ▁Technology ▁in ▁ 1 9 9 5 , ▁and ▁was ▁a ▁member ▁of ▁the ▁X i ▁chapter ▁of ▁T au ▁E psilon ▁Ph i , ▁and ▁received ▁his ▁Ph . D . ▁in ▁astronom y ▁from ▁the ▁University ▁of ▁Hawai i ▁in ▁ 2 0 0 0 . ▁ ▁Between ▁ 2 0 0 0 ▁and ▁ 2 0 0 3 ▁Tru j illo ▁was ▁a ▁post do ctor al ▁scholar ▁at ▁Cal tech . ▁In ▁ 2 0 0 3 , ▁he ▁started ▁working ▁as ▁an ▁astronom er ▁at ▁the ▁Gem ini ▁Observ atory ▁in ▁Hawai i . ▁ ▁In ▁ 2 0