1 3 ▁Tru j illo ▁became ▁head ▁of ▁the ▁Ada pt ive ▁Opt ics / T eles cope ▁Department ▁at ▁the ▁Gem ini ▁Observ atory , ▁and ▁continued ▁until ▁ 2 0 1 6 . ▁As ▁of ▁ 2 0 1 6 , ▁Tru j illo ▁is ▁assistant ▁professor ▁at ▁the ▁department ▁of ▁Astronom y ▁and ▁Planet ary ▁Science ▁at ▁Northern ▁Arizona ▁University . ▁ ▁He ▁studies ▁the ▁K ui per ▁bel t ▁and ▁the ▁outer ▁Sol ar ▁System . ▁ ▁Disc over ies ▁▁ ▁Tru j illo ▁is ▁cred ited ▁by ▁the ▁Minor ▁Planet ▁Center ▁with ▁the ▁discovery ▁and ▁co - dis cover y ▁of ▁ 5 4 ▁number ed ▁minor ▁plan ets ▁between ▁ 1 9 9 6 ▁and ▁ 2 0 1 3 , ▁including ▁many ▁trans - Ne pt un ian ▁objects ▁( T NO s ) ▁from ▁the ▁K ui per ▁bel t ▁( see ▁table ). ▁The ▁last ▁major ▁T NO , ▁Er is , ▁was ▁considered ▁by ▁him , ▁his ▁team , ▁NASA , ▁and ▁many ▁others ▁to ▁be ▁the ▁t enth ▁planet , ▁but ▁the ▁International ▁Astronom ical ▁Union ▁assigned ▁it ▁to ▁the ▁new ▁d war f ▁planet ▁and ▁pl uto id ▁status . ▁ ▁The ▁known ▁pl uto ids ▁are : ▁ ▁Qu ao ar , ▁co - dis cover ed ▁with ▁Brown ▁ ▁Sed na , ▁co - dis cover ed ▁with ▁Brown ▁and ▁Rab in ow itz , ▁possibly ▁the ▁first ▁known ▁inner ▁O ort ▁cloud ▁object ▁ ▁Or cus , ▁co