New Horizons spacecraft 'alters theory of planet formation'

By Pallab Ghosh Science correspondent, BBC News, Seattle

  • 13 February 2020

The Kuiper belt object Arrokoth is a pristine remnant of planet formation in action Scientists say they have "decisively" overturned the prevailing theory for how planets in our Solar System formed.
The established view is that material violently crashed together to form ever larger clumps until they became worlds.
New results suggest the process was less catastrophic - with matter gently clumping together instead.
The study appears in Science journal and has been presented at the American Association for the Advancement of Science meeting in Seattle.
The study's lead researcher, Dr Alan Stern, said that the discovery was of "stupendous magnitude".

"There was the prevailing theory from the late 1960s of violent collisions and a more recent emerging theory of gentle accumulation. One is dust and the other is the only one standing. This rarely happens in planetary science, but today we have settled the matter," he told BBC News.
The claim arises from detailed study of an object in the outer reaches of the Solar System. Named Arrokoth, the object is more than six billion km from the Sun in a region called the Kuiper belt. It is a pristine remnant of planet formation in action as the Solar System formed 4.6 billion years ago, with two bodies combining to form a larger one.