▁to ▁have ▁formed ▁as ▁a ▁result ▁of ▁a ▁single , ▁large ▁head - on ▁collision . ▁The ▁impact ing ▁object ▁probably ▁had ▁a ▁mass ▁compar able ▁to ▁that ▁of ▁Mars , ▁and ▁the ▁impact ▁probably ▁occurred ▁near ▁the ▁end ▁of ▁the ▁period ▁of ▁giant ▁impact s . ▁The ▁collision ▁k icked ▁into ▁orbit ▁some ▁of ▁the ▁imp actor ' s ▁mant le , ▁which ▁then ▁co ales ced ▁into ▁the ▁Moon . ▁The ▁impact ▁was ▁probably ▁the ▁last ▁in ▁the ▁series ▁of ▁mer gers ▁that ▁formed ▁the ▁Earth . ▁It ▁has ▁been ▁further ▁hypoth es ized ▁that ▁the ▁Mars - s ized ▁object ▁may ▁have ▁formed ▁at ▁one ▁of ▁the ▁stable ▁Earth – S un ▁L agr ang ian ▁points ▁( e ither ▁ ▁or ▁) ▁and ▁dr ift ed ▁from ▁its ▁position . ▁The ▁mo ons ▁of ▁trans - Ne pt un ian ▁objects ▁Pl uto ▁( Ch aron ) ▁and ▁Or cus ▁( V anth ) ▁may ▁also ▁have ▁formed ▁by ▁means ▁of ▁a ▁large ▁collision : ▁the ▁Pl uto – Ch aron , ▁Or cus – V anth ▁and ▁Earth – M oon ▁systems ▁are ▁unusual ▁in ▁the ▁Sol ar ▁System ▁in ▁that ▁the ▁satellite ' s ▁mass ▁is ▁at ▁least ▁ 1 % ▁that ▁of ▁the ▁larger ▁body . ▁ ▁Future ▁Astronom ers ▁estimate ▁that ▁the ▁current ▁state ▁of ▁the ▁Sol ar ▁System ▁will ▁not ▁change ▁dr ast ically ▁until ▁the ▁Sun ▁has ▁f used ▁almost ▁all ▁the ▁hydro gen ▁fuel ▁in ▁its ▁core ▁into ▁hel ium , ▁beginning