As a result , lunar mass planetary embryos in the inner Solar System are able to grow only to around Mars - mass , .
In the outer Solar System embryos are able to grow to more than 10x Earth - mass forming the cores of giant planets .
As a result , lunar mass planetary embryos in the inner Solar System are able to grow only to around Mars - mass , whereas in the outer Solar System they are able to grow to more than 10x Earth - mass forming the cores of giant planets .