▁Jup iter ' s . ▁The ▁planet ' s ▁orb ital ▁incl ination ▁is ▁ 8 9 . 6 5 º , ▁or ▁almost ▁edge - on ▁with ▁respect ▁to ▁Earth ▁and ▁to ▁Ke pler - 1 0 . ▁Trans its ▁have ▁been ▁observed ▁at ▁points ▁where ▁Ke pler - 1 0 c ▁has ▁crossed ▁in ▁front ▁of ▁its ▁host ▁star . ▁ ▁Ke pler - 1 0 c ▁was ▁originally ▁thought ▁to ▁have ▁a ▁mass ▁of ▁ 1 5 – 1 9 ▁Earth ▁masses . ▁ ▁With ▁a ▁radius ▁only ▁ 2 . 3 5 ▁( 2 . 3 1 ▁to ▁ 2 . 4 4 ) ▁times ▁that ▁of ▁Earth ▁( and ▁so ▁a ▁volume ▁ 1 2 – 1 5 ▁times ▁that ▁of ▁Earth ), ▁it ▁was ▁believed ▁to ▁be ▁unlikely ▁to ▁contain ▁significant ▁amounts ▁of ▁hydro gen ▁or ▁hel ium ▁gas , ▁since ▁an ▁out g ass ed ▁or ▁acc ret ed ▁hydro gen - rich ▁atmosphere ▁would ▁have ▁been ▁lost ▁over ▁the ▁ 1 0 . 6 - b ill ion - year ▁lifetime ▁of ▁the ▁Ke pler - 1 0 ▁system . ▁Instead , ▁the ▁composition ▁was ▁believed ▁to ▁be ▁mainly ▁rock y , ▁with ▁a ▁water ▁fraction ▁of ▁ 5 – 2 0 % ▁by ▁mass . ▁The ▁bulk ▁of ▁this ▁water ▁was ▁thought ▁to ▁be ▁likely ▁in ▁the ▁form ▁of ▁high - press ure ▁" hot - ice " ▁phases . ▁However , ▁in ▁July ▁ 2 0 1 7 , ▁more ▁careful ▁analysis ▁of