Cilmi-baarayaasha xiddigaha ayaa maalin walba hela meerayaal cusub. Waxaa laga yaaba in uu jiro bilyan malaayiin ah oo meerayaal ah caalamka. Aynu is barbardhigo nidaamyadan meerayaasha ah ee la helay iyo nidaamkayaga qoraxda.
Farqiga ugu weyn ee u dhaxeeya nidaamka qoraxdeena iyo nidaamyada meeraha fog ayaa u muuqda mid ka soo jeeda meelaha ay meerahaasi maraan. Meelaha qorraxda ka baxsan waxay leeyihiin meelo wareegsan oo wareegsan (oo leh meelo wareegayaal ah oo ka yar 10% meelaha wareega ee saxda ah), halka meelaha ka baxsan qorraxda ay leeyihiin ilaa 50% meelo wareegayaal ah. Exoplanets-yada leh eccentricity-yada sare ayaa laga yaabaa inaysan xasilloonayn muddada dheer. Farqiga kale ayaa ah in cabirka ugu badan ee loo yaqaan 'exoplanets' uu yahay dhul-weyne (oo ah 2-3x cabirka dhulka) halka nidaamkayaga qorraxdu uusan lahayn dhul-weyne.