История изменений

http://en.wikipedia.org/wiki/Protoplanetary_disk

Ммм, с теориями там похоже вообще все плохо: http://en.wikipedia.org/wiki/Nebular_hypothesis

The formation of planets like Uranus and Neptune is more problematic, since no theory has been capable of providing for the in situ formation of their cores at the distance of 20–30 AU from the central star. One hypothesis is that they initially accreted in the Jupiter-Saturn region, then were scattered and migrated to their present location.

Но солнечный ветер - фактор, да. Пойду поковыряю пару валяющихся книг по среднеобывательской космологии.

http://en.wikipedia.org/wiki/Protoplanetary_disk

Ммм, с теориями там похоже вообще все плохо: http://en.wikipedia.org/wiki/Nebular_hypothesis

he formation of planets like Uranus and Neptune is more problematic, since no theory has been capable of providing for the in situ formation of their cores at the distance of 20–30 AU from the central star. One hypothesis is that they initially accreted in the Jupiter-Saturn region, then were scattered and migrated to their present location.