Before Jupiter settled into its current ambit , the monolithic planet come up in like a wrecking glob , tangle its way through the early solar system and bankrupt a first generation of inner planets . Earth and the other rocky planets afterwards blend out of the debris , according tofindingspublished inProceedings of the National Academy of Sciencesthis week .
The structure of our solar system is unlike hundreds of other planetary systems : While known extrasolar systems have large planets that orbit near to their host star , we ’ve vex down - mass inner planets that are far from the Lord’s Day . " One of the most interesting feature of speech is the absence seizure of planets inside the orbit of Mercury,“Greg Laughlin from the University of California , Santa Cruz , says in anews release . " The standard issue planetary system in our extragalactic nebula seems to be a Seth of super - globe with alarmingly short orbital periods . Our solar system is bet increasingly like an geek . "
To see why we ’re such an unusual member of the astronomical world census , Laughlin andCaltech ’s Konstantin Batyginmodeled planetary geological formation in the early solar system . Jupiter migrate inwards , they discover , from an orbit of more than 5 astronomical units ( AUs ) to around 1.5 Au ( where Mars ' orbit is today ) . This was then follow by an outward-bound orbital migration to its current office — activate by the organization of Saturn .
This inward - then - outbound roving may excuse the gaping fix in our inner solar system , as well as the lowly mass of inner planets . It ’s possible that prior to Jupiter ’s inward migration , planet form close to the Lord’s Day were on their way to becoming tiptop - solid ground — planets more monumental than Earth but smaller than Neptune . According to this pretense , gravity from Jupiter ’s inward migration shepherded these low world-wide precursors ( along with asteroids and other body ) into close - knit , overlapping elliptic ambit .
This would have initiate a shower of collision in the privileged solar system , and any preexist planet and planetesimals near the sun would have been smashed into pieces and commit hurtle towards a fiery decease . " It ’s a very efficient physical cognitive process , " Batygin says in auniversity command . " You only need a few Earth masses worth of material to force tens of Earth raft deserving of planets into the sunshine . "
The remaining mass - exhaust debris of planet - gain material later formed into the second multiplication inside rocky planets : Mercury , Venus , Earth , and Mars . That ’s consistent with evidence that these little , terrestrial planets with thin atmospheres are untested than the out planets .
found on these calculations , stars that harbor giant planets with orbital periods long than 100 days are improbable to host multiple airless - in planets . In the diagram to the right field , you could see how most extrasolar planets small than Jupiter are much closer to their host stars than our inmost planets are to the sun .
Furthermore , by the meter Earth formed , the disk of hydrogen and He gun was long gone . Most super - Earths orbiting other star have a substantial hydrogen air since they take form when the gas was still abundant in their global disk . " Ultimately , what this means is that planet sincerely like Earth are intrinsically not very common,“Batygin add .
Images : K.Batygin / Caltech ( top ) , Batygin and Laughlin , 2015 PNAS ( mediate )
