▁the ▁K ui per ▁bel t ▁and ▁of ▁anom alous ▁materials ▁within ▁it ▁suggest ▁that ▁the ▁Sun ▁formed ▁within ▁a ▁cluster ▁of ▁between ▁ 1 , 0 0 0 ▁and ▁ 1 0 , 0 0 0 ▁stars ▁with ▁a ▁diameter ▁of ▁between ▁ 6 . 5 ▁and ▁ 1 9 . 5 ▁light ▁years ▁and ▁a ▁collect ive ▁mass ▁of ▁. ▁This ▁cluster ▁began ▁to ▁break ▁apart ▁between ▁ 1 3 5 ▁million ▁and ▁ 5 3 5 ▁million ▁years ▁after ▁formation . ▁Several ▁simulations ▁of ▁our ▁young ▁Sun ▁interact ing ▁with ▁close - pass ing ▁stars ▁over ▁the ▁first ▁ 1 0 0 ▁million ▁years ▁of ▁its ▁life ▁produce ▁anom alous ▁or bits ▁observed ▁in ▁the ▁outer ▁Sol ar ▁System , ▁such ▁as ▁det ached ▁objects . ▁ ▁Because ▁of ▁the ▁conservation ▁of ▁angular ▁momentum , ▁the ▁ne b ula ▁sp un ▁faster ▁as ▁it ▁col lapsed . ▁As ▁the ▁material ▁within ▁the ▁ne b ula ▁cond ensed , ▁the ▁atoms ▁within ▁it ▁began ▁to ▁col lide ▁with ▁increasing ▁frequency , ▁converting ▁their ▁kin etic ▁energy ▁into ▁heat . ▁The ▁centre , ▁where ▁most ▁of ▁the ▁mass ▁collected , ▁became ▁increasing ly ▁hot ter ▁than ▁the ▁surrounding ▁disc . ▁Over ▁about ▁ 1 0 0 , 0 0 0 ▁years , ▁the ▁compet ing ▁forces ▁of ▁gravity , ▁gas ▁pressure , ▁magnetic ▁fields , ▁and ▁rotation ▁caused ▁the ▁contract ing ▁ne b ula ▁to ▁fl atten ▁into ▁a ▁spin ning ▁pro top lan et ary ▁disc ▁with ▁a ▁diameter ▁of ▁about