New theory to explain why planets in our solar system have different compositions

March 22, 2018 by Bob Yirka, Phys.org report
Credit: CC0 Public Domain

A team of researchers with the University of Copenhagen and the Museum für Naturkunde, Leibniz-Institut für Evolutions has come up with a new explanation regarding the difference in composition of the planets in our solar system. In their paper published in the journal Nature, they describe their study of the calcium-isotope composition of certain meteorites, Earth itself, and Mars, and use what they learned to explain how the planets could be so different. Alessandro Morbidelli with Observatoire de la Côte d'Azur in France offers a News & Views piece on the work done by the team in the same journal issue.

As Morbidelli notes, most planetary scientists agree that the in our solar system had similar origins as small rocks orbiting the sun, comprising the , which collided and fused, creating increasingly larger rocks that eventually became protoplanets. But from that point on, it is not clear why the planets turned out so differently. In this new effort, the researchers have come up with a new theory to explain how that happened.

The protoplanets all grew at the same rate, the group suggests, but stopped growing at different times. Those that were smaller, they continue, stopped growing sooner than those that were larger. During this time, they further suggest, material was constantly being added to the disk. Early on it, it appears that the composition of the material was different from the material that came later, which explains why the we see today have such differences in composition.

The researchers developed their theory after studying the calcium-isotope composition of several meteorites called angrites and ureilites, as well as that of Mars and Earth, and also from the asteroid Vesta. Calcium isotopes, they note, are involved in the formation of rock, and because of that, offer clues about their origins. The researchers found that isotopic ratios in samples correlated with the masses of their parent planets and asteroids, which they claim provides a proxy for their accretion timeline. And that, they further claim, provides evidence of the different compositions of the planets, as the smaller ones ceased accreting material while the larger ones continued to add material that was different from what had come before.

Explore further: Study sheds new light on how Earth and Mars were created

More information: Martin Schiller et al. Isotopic evolution of the protoplanetary disk and the building blocks of Earth and the Moon, Nature (2018). DOI: 10.1038/nature25990

Abstract
Nucleosynthetic isotope variability among Solar System objects is often used to probe the genetic relationship between meteorite groups and the rocky planets (Mercury, Venus, Earth and Mars), which, in turn, may provide insights into the building blocks of the Earth–Moon system. Using this approach, it has been inferred that no primitive meteorite matches the terrestrial composition and the protoplanetary disk material from which Earth and the Moon accreted is therefore largely unconstrained6. This conclusion, however, is based on the assumption that the observed nucleosynthetic variability of inner-Solar-System objects predominantly reflects spatial heterogeneity. Here we use the isotopic composition of the refractory element calcium to show that the nucleosynthetic variability in the inner Solar System primarily reflects a rapid change in the mass-independent calcium isotope composition of protoplanetary disk solids associated with early mass accretion to the proto-Sun. We measure the mass-independent 48Ca/44Ca ratios of samples originating from the parent bodies of ureilite and angrite meteorites, as well as from Vesta, Mars and Earth, and find that they are positively correlated with the masses of their parent asteroids and planets, which are a proxy of their accretion timescales. This correlation implies a secular evolution of the bulk calcium isotope composition of the protoplanetary disk in the terrestrial planet-forming region. Individual chondrules from ordinary chondrites formed within one million years of the collapse of the proto-Sun7 reveal the full range of inner-Solar-System mass-independent 48Ca/44Ca ratios, indicating a rapid change in the composition of the material of the protoplanetary disk. We infer that this secular evolution reflects admixing of pristine outer-Solar-System material into the thermally processed inner protoplanetary disk associated with the accretion of mass to the proto-Sun. The identical calcium isotope composition of Earth and the Moon reported here is a prediction of our model if the Moon-forming impact involved protoplanets or precursors that completed their accretion near the end of the protoplanetary disk's lifetime.

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h20dr
1.3 / 5 (16) Mar 22, 2018
If you look at it from a intelligent design veiwpoint, it makes perfect sense for interplanetary colonization.
Guy_Underbridge
4.7 / 5 (12) Mar 22, 2018
If you look at it from a intelligent design veiwpoint, it makes perfect sense
If you look at it from a intelligent design viewpoint, anything makes 'sense' as long as it's called intelligent design.
Bart_A
1.3 / 5 (12) Mar 22, 2018
Guy, you hit the nail on the head. Looking at it the other way, a lot of things don't make any sense without intelligent design in the picture. And will never make any sense in the future, either.
jonesdave
4 / 5 (16) Mar 22, 2018
Guy, you hit the nail on the head. Looking at it the other way, a lot of things don't make any sense without intelligent design in the picture. And will never make any sense in the future, either.


ID is just Creationism by another name. It therefore tells us precisely nothing. It sure as hell isn't science.
granville583762
3.8 / 5 (5) Mar 22, 2018
We and our planets are the stuff of Stars

Whichever galaxy you go to it, is composed of exactly the same material as our galaxy and consequently our solar system is constructed of the same material of the clouds that are condensing under gravity round billions of stars and billions of proto stars where the clouds are seeded with the heavier elements formed in stars when they ignite or go supernova and eject the heavier elements. The elements that are found in planets including the elements in our self's, are from the stars that got their original construction element, hydrogen from the vacuum of space. Even the visiting stars Scholz's star for example could only add the same elements to our solar system as our sun has because they are both constructed of the same material and it make no difference which galaxy Scholz's star originally came from.
rrwillsj
4 / 5 (4) Mar 22, 2018
As long as we're telling fairytales...

The gases that make up the stars are of the same chemical composition as biologically produced flatulence. Therefore, the only possibly believable conjecture is that the stars are the poop produced by the godlings crapping all over the universe.

Anyone who denies these undeniable facts? Has to be an atheist scoundrel!

And, uhh no, the elemental composition of the galaxies can vary quite a bit. Most likely depending on at which stage of development a galaxy miscarries. Halting stellar formation cycles that refresh the gas clouds.

ID is stuporstiton at it's most ignorant.

As our technology improves and the sciences advance, what we see actually observe is SD. Stupid Design failures.

Here in our Solar System alone, there is only one Living World. You can count to 'one' cantcha?

Only ONE planet that can sustain a biosphere.

What we see in nearby systems, is even stronger evidence for the Stupid Design theory.
granville583762
3.8 / 5 (5) Mar 22, 2018
WhatsApping our neighbours on Andromeda, they look just like us!

Well what about evolution of the species on our planet, were using the same skeleton stretched and poked here and there, ever since fish crawled out the sea billions of years ago when fish devolved backbones, are backbone legs and muscles have not evolved for walking on two feet everything has just been using the same basic skeleton stretched to sort of do the job. There is not the same ingenuity that has been gone into at the cellular level in the in the rods and cones enabling the eye to see single photons, it is a mismatch of intelligent design but expect more of the same when we start WhatsApping our neighbours on Andromeda, they look just like us!
rrwillsj:- As long as we're telling fairytales... .

granville583762
4.5 / 5 (4) Mar 22, 2018
The variation in our solar system planets is mirrored throughout all the trillion upon trillion solar systems in the trillion upon trillion galaxies where are neighbours are WhatsApping each other just as we are. As you point out the variation in composition with distance is totally due to the proto star sun during its formation. In fact the distance the ejected material reaches can be calculated.

When nova star forming solar system exploded it ejected heavier fragments into outside and large clouds of interstellar gas at larger distance (mostly the radiative pressure accounts to it). Therefore it's not so strange, that gaseous planets were formed at perimeter of solar system.

ddaye
5 / 5 (2) Mar 22, 2018
The existence of the excessively exposed nerve in the human elbow (called the "crazy bone" in the US), and certain male anatomy exposed such that a few grams of well placed force can drop a fighting man to his knees, are proof that there is also a Stupid Designer at work in the cosmos. It will be found that the shortcomings of Intelligent Design are largely remedied when Stupid Design is incorporated into the theory.
TheGhostofOtto1923
5 / 5 (4) Mar 23, 2018
Guy, you hit the nail on the head. Looking at it the other way, a lot of things don't make any sense without intelligent design in the picture. And will never make any sense in the future, either
Religionists. You take their insanity and shove it in their face and they take it as a complement.

Unbelievable.
TheGhostofOtto1923
5 / 5 (2) Mar 23, 2018
certain male anatomy exposed such that a few grams of well placed force can drop a fighting man to his knees, are proof that there is also a Stupid Designer at work
Well sure. God would have provided humans with off switches for use by enlightened ones like shaolin priests.

Right bart?
Jonasb
3.5 / 5 (4) Mar 23, 2018
"The protoplanets all grew at the same rate, the group suggests, but stopped growing at different times."

I'm curious if everyone thinks that the planets have stopped growing, and if so, at what definitive point did that happen?

In my opinion, every single meteor/meteorite, (even the ones that burn up in our atmosphere) is still adding mass to the any of the planets, no matter how slow it is happening.
granville583762
3.8 / 5 (5) Mar 23, 2018
The planets are forever growing

The constant barrage of cosmic rays, neutrino's, meteorites and other countless space debris has been raining down earth for 5 billion years and is continuing like the ingredients of life is continually increasing the total mass of the Earth, so your correct the planets are growing in size and mass as we inkly type!

Jonasb:- "The protoplanets all grew at the same rate, the group suggests, but stopped growing at different times."

I'm curious if everyone thinks that the planets have stopped growing, and if so, at what definitive point did that happen?

In my opinion, every single meteor/meteorite, (even the ones that burn up in our atmosphere) is still adding mass to the any of the planets, no matter how slow it is happening.

jonesdave
3 / 5 (6) Mar 23, 2018
http://www.skyandtelescope.com/astronomy-news/history-and-sky-lore/velikovskys-venus/ that our neighbor world was spawned by Jupiter 3,500 years ago and nearly struck Earth — twice.


'Scientifically illiterate' would be a better choice of words than 'controversial'! The guy was a moron. Science certainly wasn't his forte.
jonesdave
3.5 / 5 (8) Mar 23, 2018
...................or new physics :)


Whatever 'new' physics there may be, it will still obey the fundamental laws of physics. Which is why Velikovsky was a bit of a joke. He didn't care about them. When it was pointed out to him, he just shrugged it off. His bizarre misinterpretation of myth said it happened, therefore it did! Pseudoscience 101.
jonesdave
3.1 / 5 (7) Mar 23, 2018
^^^^^^Nope. Something as stupid as having Venus pop out of Jupiter and go careering round the solar system, just to fit in with his screwed up interpretations of mythology, deserves no consideration whatsover. He re-dated a bunch of pharaohs to fit with his bizarre beliefs. He was shown to be wrong through carbon dating, among other things. He couldn't get science right, and he couldn't get the rest of his mythology rubbish to fit together either.
He was a moron. I'll go further - he was a world class moron. Anybody that gives that crap any credence is, by definition, scientifically illiterate.
jonesdave
3.3 / 5 (7) Mar 23, 2018
According to Velikovsky (1895-1979), about 4000 years ago a giant volcano on Jupiter erupted and spewed a vast glob of debris into space, leaving the Great Red Spot behind as a permanent scar. The red hot lump ejected from Jupiter (referred to as a comet by Velikovsky) wandered into the inner Solar System, repeatedly crossing the Earth's orbit and in fact often passing close to our helpless planet in the following millennia.


All of which is scientifically impossible. So, your point is? That we should give credence to absolute loons because.........................?

rrwillsj
4.2 / 5 (5) Mar 23, 2018
mack, seriously? All the retrograde rotation of Venus proves, is? Not one damn thing!

The Titius-Bode Laws and all the other speculations that the Cosmos was orderly and organized? Just as Human wisdom dictated.

Modern observations of other star systems, displays an enormous range of wildly orbiting planets in no discernible order.

It is our monkey instincts, overtaxing our intellects, that demands that the universe obeys our aesthetic sensibilities.

So far, the most accurate interpretation of what we are actually seeing? Planetary System formation results from chaotic processes. With hefty dosages of random uncertainty amid spectacularly violent planetesimal collisions.

There is nothing subtle nor precise about the Law of Gravity, the Laws of Thermodynamics and Newton's Laws of Motion.

Leaving a universe strewn with failed worlds, capricious debris and utter confusion.

I blame that asshat jokester, the Coyote Goddess. For playing dice with reality.
rrwillsj
4.2 / 5 (5) Mar 24, 2018
The only book available is neatly printed with the letter 'A''. Titius-Bode's 'Law' requires that all the books in the library have pages neatly printed with the letter 'A'.

When I am actually able to read the other books? I discover that pre-assumption is incorrect.

The other books have many different letters, printed in no discernible order or coherence.

Where upon it becomes obvious that the Titius-Bode guesstimate is fallacious and false outside of our Solar System 'Book".

Billions of lotto tickets were sold and only one ticket's holder wins the grand prize.

A Scientific 'Law' explains why things work the way they work. All the time and everywhere. Gravity of Mass attracts all other mass. Thermodynamics always invoices your existence for a cost greater than you are willing to pay. Laws of Motion are why you are always a clumsy klutz.

A billion losers and only one winner? We may feel special but we are the result not the cause of our good fortune.
torbjorn_b_g_larsson
4 / 5 (4) Mar 24, 2018
The paper makes an intriguing observation between isotope composition and size, a proxy for accretion time. It supports the modern pebble formation (short timescale) and migration (water on inner planets) scenarios, and must fit the system pathway history in some way.

However there are some problems. Why did accretion happen over different times instead of different rates, and why is the new history of Earth - same size planetesimals that did not meet until after 60 Myrs, and then somehow fulfilled the "Mars size impactor" orbital momentum result - so complicated (unlikely)?

What is not intriguing is the religious, against evidence, based creationism/ID and Velikovksy stories. Ttius-Bode law did not work, does not predict the absence of planets between Earth and Mars or Neptune (or potentially Planet Nine) https://en.wikipe...Bode_law , so was also rejected long since.
TheGhostofOtto1923
1 / 5 (2) Mar 24, 2018
The other books have many different letters, printed in no discernible order or coherence
But willis they all use the same letters. And rules of grammar etc. In contrast to your shitty prose-poecy posts.
The Titius-Bode Laws and all the other speculations that the Cosmos was orderly and organized? Just as Human wisdom dictated... Modern observations of other star systems, displays an enormous range of wildly orbiting planets in no discernible order
Willis says that because we dont know all the conditions that created the star systems we observe, then we will never know because its just more poetic that way I guess.

You get stoned a lot there willis? Might this explain why you think the world appreciates your stream-of-consciousness musings instead of simple facts and logic?

Because this is a science site you know, not a trash dump for shitty poetry and made-up facts.
blazmotronic
1 / 5 (3) Mar 25, 2018
God spoke the Earth moon sun solar system Galaxy Universe into existence! No act of
human knowledge or computing power can figure it out...thus the confusion in the
science world. The laws of physics tell us how everything works ..but not how everything
came to be!
rrwillsj
1 / 5 (1) Mar 26, 2018
blazingmoronic, the deity insists to me, that it did not cause this kludged up mess we call a universe.

'Laws' of Science are just temporary fudge factors. When scientists can't figure out if they should prevaricate or vacillate? In the hopes that someone will eventually figure out how to resolve the quandaries.

By 'Temporary'. I mean a few hundred billion years in Time and about a hundred billion parsecs in Space. Don't wait up!

blazingmoronic, Unless you are worshiping the Trickster Coyote God or Loki? Or, a Chthonic entity such as Uranus, Váruṇa or Lung? It is unfair and insulting of you to blame the deity for how badly the cosmos has turned out. No Intelligent Design was involved. It has been straight out Stupid Design since the accident that broke Reality and left such an incoherent mess behind.

Why do I. Mister Knowitnotatall, accept Science, as an almost reasonable explanation for our world?

Cause the guys who can blow up cities? Scare me!

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