1.When the planetary migration occurs under the tidally interaction of a planet and a disk of gas or a planetesimal, the orbital parameters, especially, semi-major axis, of this planet will be altered.
2.When the planetary migration occurs under the tidally interaction of a planet and a disk of gas or a planetesimal, the orbital parameters, especially, semi-major axis, of this planet will be altered.
3.Thus, if the majority of the small amounts of water in a planetesimal reaches a planetary surface as its magma solidifies, this would be enough to form oceans that are similar to Earth's.