PLANETS either form very rarely, or the prevailing model of how they form is wrong, say researchers who have been studying the dusty discs from which they are born.
Their results exacerbate a longstanding quandary. The theory is that small particles in the discs of dust and gas surrounding a star gradually collect together due to gravity. But this process would take 10 to 20 million years to make gas giants such as Jupiter and Saturn, and even longer, perhaps 100 million years, to make rocky planets such as Earth. Yet such discs of debris haven’t been seen around stars…
