People who have been claiming the Earth is flat may have been right once, they just said their idea was billions of years too late. Scientists at the University of Central Lancashire (UCLan) have discovered that newly formed planets may have a flatter shape before becoming rounder.
It is known that planets form from protoplanetary disks - rings of dust and gas around stars - but exactly how they are formed is still debated. The most commonly accepted theory is called core accretion, in which dust particles begin to stick together, forming larger and larger objects until they grow into planets. Another less popular but still plausible model is called disk instability, which is thought to occur much faster, as the disk cools and collapses into clumps that turn into planets.
In the new study, the UCLan research team used supercomputers to simulate the planet formation process, with the aim of studying an aspect that has been neglected - what are young planets shaped like?
Dr Dimitris Stamatellos, a co-researcher on the study, said: "We have been studying planet formation for a long time, but it had never occurred to us to examine the shapes of planets as they form in simulations. People had always assumed they were spherical."
Instead, the researchers found that when planets formed through the disk instability method, they did not grow outward uniformly and remained spherical - instead, they tended to accumulate more material at the poles than at the equator, stretching them into "oblate spheroids," a flattened elliptical shape. As young planets grow, they will eventually, of course, take on the familiar spherical shape we have.
While these are just simulation results for now, observations of young planets to see if any have such strange shapes could help confirm or rule out the disk instability method of planet formation, the team said.
The research has been accepted for publication in the journal Astronomy and Astrophysics Letters (PDF).