▁outer ▁layers ▁as ▁a ▁planet ary ▁ne b ula ▁and ▁leaving ▁behind ▁a ▁stell ar ▁rem nant ▁known ▁as ▁a ▁white ▁d war f . ▁In ▁the ▁far ▁distant ▁future , ▁the ▁gravity ▁of ▁passing ▁stars ▁will ▁gradually ▁reduce ▁the ▁Sun ' s ▁ret inue ▁of ▁plan ets . ▁Some ▁plan ets ▁will ▁be ▁destroyed , ▁others ▁e ject ed ▁into ▁inter stell ar ▁space . ▁Ult imately , ▁over ▁the ▁course ▁of ▁tens ▁of ▁bill ions ▁of ▁years , ▁it ▁is ▁likely ▁that ▁the ▁Sun ▁will ▁be ▁left ▁with ▁none ▁of ▁the ▁original ▁bodies ▁in ▁orbit ▁around ▁it . ▁ ▁History ▁ ▁Ide as ▁concerning ▁the ▁origin ▁and ▁fate ▁of ▁the ▁world ▁date ▁from ▁the ▁earliest ▁known ▁writ ings ; ▁however , ▁for ▁almost ▁all ▁of ▁that ▁time , ▁there ▁was ▁no ▁attempt ▁to ▁link ▁such ▁theories ▁to ▁the ▁existence ▁of ▁a ▁" S olar ▁System ", ▁simply ▁because ▁it ▁was ▁not ▁generally ▁thought ▁that ▁the ▁Sol ar ▁System , ▁in ▁the ▁sense ▁we ▁now ▁understand ▁it , ▁existed . ▁The ▁first ▁step ▁toward ▁a ▁theory ▁of ▁Sol ar ▁System ▁formation ▁and ▁evolution ▁was ▁the ▁general ▁accept ance ▁of ▁hel i oc entr ism , ▁which ▁placed ▁the ▁Sun ▁at ▁the ▁centre ▁of ▁the ▁system ▁and ▁the ▁Earth ▁in ▁orbit ▁around ▁it . ▁This ▁concept ▁had ▁developed ▁for ▁mill enn ia ▁( Ar ist arch us ▁of ▁Sam os ▁had ▁suggested ▁it ▁as ▁early ▁as ▁ 2 5 0 ▁BC ), ▁but ▁was ▁not ▁widely ▁accepted ▁until ▁the ▁end ▁of ▁the ▁