ALTHOUGH many more planets are being discovered outside the solar system, none of them looks anything like our own planets. And it is possible that they formed in a completely different way, making our planetary system rather unique.
In the traditional model of planet formation, the dust in a disc of gas around a star gradually clumps together into rocks, which eventually merge to make planetary cores. The cores then accumulate gaseous atmospheres. In this model, gas giants such as Jupiter form in the relatively cooler outskirts of the system.
But this model does not fully explain the formation of…
