New Horizons spacecraft ‘alters theory of planet formation’
Image copyright NASA/JHUAPL/SWRI/ROMAN TKACHENKOScientists 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”.
Image copyright NASA/BILL INGALLS Image caption The moment Alan Stern (L) had confirmation that New Horizons had flown by the Kuiper Belt object“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 emerged 4.6 billion years ago, with two bodies combining to form a larger one.
Scientists obtained high-resolution pictures of Arrokoth when Nasa’s New Horizons spacecraft flew close to it just over a year ago. It gave scientists their first opportunity to test which of the two competing theories was correct: did the two components crash together or was there gentle contact?
The analysis by Dr Stern and his team could find no evidence of violent impact. The researchers found no stress fractures, nor was there any flattening, indicating that the objects were squashed together gently.
“This is completely decisive,” said Dr Stern. “In one fell swoop, the flyby of Arrokoth was able to decide between the two theories.”
Image copyright LUND OBSERVATORY Image caption The newer gentle clumping theory was developed 15 years ago by Prof Anders JohansenHe is bullish because these so-called Kuiper belt objects have largely remained the same since the formation of the Solar System. They are, in effect, perfectly preserved fossils from this distant time.
The newer gentle clumping theory was developed 15 years ago by Prof Anders Johansen at Lund Observatory in Sweden. At the time he was a young PhD student. The idea emerged from computer simulations.
After speaking to Dr Stern, I broke the news to Prof Johansen that his theory had been confirmed. There was a pause on the line before he replied that he “felt great”.
He added: “It is a special moment. I remember when I was a PhD student and feeling very nervous about these new results because they were very different to the ones before. I was worried that there was an error in my code or that I had made a calculation error.
“And then when you see these results confirmed from actual observations it is a real relief.”
Image copyright ANDERS JOHANSEN Image caption Anders Johansen marks the confirmation of his theory with his daughter LauraProf Johansen commemorated the occasion with a pizza and coke with his family.
Engineer Dr Maggie Aderin-Pocock, who co-presents the BBC’s Sky at Night programme, cautioned against toppling a theory based on the observation of one object, but said that Dr Stern’s interpretation “makes a lot of sense”.
“It is nice to have this evidence because the crashing together theory was a nice theory, but there were some challenges to it. Why did the objects stick together and not bounce apart. There was a lot that didn’t add up.”
When Arrokoth was discovered six years ago, it was known only by its designation 2014 MU69. At the time of the New Horizons flyby, it had been given the informal name Ultima Thule. While that name came from a classical and medieval term for a far-off place at the borders of the known world, its use by Nazi occultists as the mythical homeland of the Aryan race caused controversy.
The official name Arrokoth is a Native American term meaning “sky” in the Powhatan/Algonquian language.
Read more at www.bbc.co.uk
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Andy Rowlands
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I had never been led to believe ‘material violently crashed together’ formed the planets, it was a gradual accumulation over millions of years.
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Robert Beatty
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Hi Andy,
I am interested to know how do you think the Moon formed?
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Peter C
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The impact collider theory of the Moon’s formation may be the predominant theory, but it is not the only one.
Dr Andrew Prentice (Modern Lapacian Theory) has applied his theory to the moon.
According to Prentice the Moon formed at the same time as the Earth. The contracting dust cloud which formed the Earth shed a ring of gas which condensed into the Moon.
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JDHuffman
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Correct Peter, none of the “theories” from established science can explain the moon. Moon is clearly not rotating on its axis, so they try to create the pseudoscience that the moon is rotating in sync with its orbit. But that only works if they redefine “orbiting”. They have so much to cover up.
Nothing new.
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Matt
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Hi JD. My over simple thought is an area of the moon has greater mass than the rest of the moon and the greater mass area creates a gravitational lock with earth meaning no rotation.
JDHuffman
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That’s exactly what I am referring to. That’s the pseudoscience that is taught. It is all over the internet, and people swallow it readily.
Herb Rose
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Hi Robert,
Here’s another theory. The sun formed without planets around it. It”burned” for billions years creating ashes (heavier elements). When the amount of ash became to great it exploded sending the ash into space then continues. to “burn”. (This is why after a nova a sun is seen at the center of the explosion.) The ash is not in the form of dust but molten clumps (asteroids, Kulper belt) that can merge together forming planets. If they cool enough they are not able too coalesce and become separate entities (moons). or there is the possibility as the sun continues to burning produce ash subsequent explosions deposit more matter around the existing trash piles (planets). Why would gravity cause the lightest element (hydrogen) to concentrate in the center of the gravitational field and the heavier elements to concentrate on the edges?
Herb
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chris
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It’s probably a combination of both violent and gentle. The limit to the violent is the point at which the material would leave the gravitational pull of the larger object thus separating the pieces. But taking a look at meteor craters planets to gain some mass through violent means as well.
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Alan
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Makes sense. In the solar nebula, objects stick together in the thick clouds of dust. All the crashing came later after the planets were formed.
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Robert Beatty
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The Arrokoth object appears to have joined at a time when both had molten cores, but hardening skins. This is consistent with a launch from Jupiter during the fourth quartile eruption phase illustrated at https://bosmin.com//PSL/TNOs4.jpg Under these circumstances, the objects are from a time much later than a “pristine remnant of planet formation in action as the Solar System emerged 4.6 billion years ago, with two bodies combining to form a larger one.”
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