From ETH Zurich.
Planetary scientists have long debated where the material that formed our Earth comes from. Despite its location in the inner Solar System, they consider it likely that 6–40 per cent of this material must have come from the outer Solar System, i.e., beyond Jupiter.
For a long time, material from the outer Solar System was considered necessary to bring volatile components such as water to Earth. Accordingly, there must also have been an exchange of material between the outer and inner Solar Systems during the formation of the Earth. But is that really true?
“We were truly astonished”
Planetary scientists Paolo Sossi and Dan Bower, from ETH Zurich, compared existing data on the isotopic ratios of a wide range of meteorites, including those from Mars and the asteroid Vesta, with those of Earth. Isotopes are sibling atoms of the same element (same number of protons) that have a different mass (different number of neutrons).
The researchers analysed this data in a new way and arrived at a surprising conclusion: the material that makes up Earth originates entirely from the inner region of the Solar System.
Material from the outer Solar System, by contrast, is likely to account for less than two per cent of Earth’s mass, or even nothing at all. The corresponding study has just been published in the journal Nature Astronomy.
“Our calculations make it clear: the building material of the Earth originates from a single material reservoir,” says Sossi. His colleague Bower adds: “We were truly astonished to find that the Earth is composed entirely of material from the inner Solar System distinct from any combination of existing meteorites.”
For their study, the ETH researchers used existing data on ten different isotopic systems from meteorites, and analysed them using a specialised statistical method. Previous studies have mostly considered only two isotopic systems.
“Our studies are actually data science experiments,” says Sossi. ‘We carried out statistical calculations that are rarely used in geochemistry, even though they are a powerful tool.’
Isotope signature reveals origin
Isotopes in meteorites have long been used by researchers to determine the origin of celestial bodies, i.e. which part of the Solar System they come from. Historically, however, only the various isotopes of the element oxygen could be used to determine their provenance.
It was not until the early 2010s that an American researcher discovered that other isotopes, such as of chromium and titanium, could also be used for this purpose. This has enabled researchers to classify meteorites into two categories: non-carbonaceous ones, which form exclusively in the inner Solar System, and carbonaceous ones, which contain more water and carbon and originate in the outer Solar System.
The new analysis reveals that the Earth is composed entirely of non-carbonaceous material. No evidence for the previously suspected exchange between the outer- and inner solar system reservoirs was found.
Therefore, the Earth grew within a relatively static system, incorporating its smaller neighbouring planets as it grew. This also implies that most volatile elements, such as water, must have already been present in the inner Solar System.
Jupiter acts as a material barrier
But why are there two distinct material reservoirs in our Solar System? Researchers assume that our Solar System split into two reservoirs during its formation due to Jupiter’s rapid growth and size. The gravity of the gas giant tore a gap in the protoplanetary disc orbiting the young Sun. These discs are ring-shaped and consist of gas and dust; they are the birthplace of planets. Jupiter prevented material from the outer solar system from entering the inner region. However, the extent to which this barrier was permeable remained unclear until now.
In their new analysis, the two ETH researchers demonstrate that almost no material from beyond Jupiter flowed towards Earth. “Our calculations are very robust and rely solely on the data itself, not on physical assumptions, as these are not yet fully understood,” Bower emphasises. The analysis also shows that Earth’s material composition is similar to that of Vesta and Mars.
The researchers also suspect that Venus and Mercury lie on the same line. “Based on our analysis, we can theoretically predict the composition of these two planets,” says Paolo Sossi. However, he cannot verify this analytically, as no rock samples from Mercury and Venus, which are the two innermost planets in the Solar System, are currently available to the researchers.
New light on the formation history
“Our results shed new light on the formation history of our Earth and the other rocky planets,” says Sossi.
Sossi and his team intend to follow up by investigating why there was sufficient water in the hot, inner Solar System to form the Earth’s oceans. Furthermore, they will examine whether these processes can be applied to exoplanetary systems.
“Until then, however, Dan and I will have to engage in many heated debates about the material composition of Earth and its neighbouring planets, because the scientific discourse over the building blocks of Earth is far from over, despite the new findings,” says Sossi.
Reference
Sossi PA, Bower DJ. Homogeneous accretion of the Earth in the inner Solar System, Nature Astronomy, 27 March 2026, DOI: 10.1038/s41550-026-02824-7
I was reminded of the clumping phenomena discovered on the ISS
I apologise in advance, this is way off topic, but… it is a hugely (given the state of UK judiciary) surprising finding.
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The British Indian Ocean Territory (BIOT) Supreme Court has ruled that Chagossians hold a lawful Right of Abode in the Chagos Archipelago. In a huge blow to Starmer…
This causes issues for the treaty signed but not ratified with Mauritius, which operates on the assumption that there is no resident population on the island. Newsflash – there is… – GF
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Bad news for UvdL (Ursula..)
The EU is looking to seize on Keir Starmer’s Chagos surrender deal and pursue fishing access in the territory from Mauritius. Brussels is hoping to expand its agreement, which could see French and Spanish vessels granted access to vast ocean areas surrounding the archipelago.
A Commission document released this month showed that EU officials are closely monitoring Britain’s Chagos agreement. GBN
With friends like that…
Perhaps I am getting old, but I learned about this in High School Science, the Accretion theory, there was no talk of, there must have been an exchange with the outer solar system during Earths formation.
“The researchers analysed this data in a new way and arrived at a surprising conclusion: the material that makes up Earth originates entirely from the inner region of the Solar System.”
an exchange with the outer solar system
That sounds awfully like the UK and EU
Can’t wait to see the look on their face when they get to the part where Earth was obliterated and reformed with a Moon and Oceans, one billion years after it formed..
Oh, is that actual real science. You mean there is no ‘consensus’? – Not settled? …how odd….
Italy to Keep Coal Power Stations Open for Another Decade
Daily Sceptic
Interesting.
Just think about this Earth creation process from beginning to today.
It is an amazing happenstance! Some would say miraculous.
There are lots of solar systems similar to ours in the universe. I wonder what things look like there.
Astronomers are getting closer to being able to find Earth-like planets around other stars.
We may have some answers before too long. We may be able to detect signs of life there, if there are any.
My understanding is “earth like” planets have been discovered. Not many.
The definition of earth like should include being in the not to hot, not to cold, just right habitable zone distance from the sun and liquid water.
I do not recall if any of those “earth like” planets that have been discovered include all of the qualifiers.
It is very convincing that an earth like planet with liquid water in a habitable zone will have life of some form. The question then becomes is the life evolved to higher levels with intelligence.
Earth like also needs to include about the same size as well.
Wouldn’t a larger planet that is either (a) less dense or (b) that is spinning fast enough to compensate for a greater mass and gravity work too?
If I interpret what you’re trying to get to correctly, it’s the amount of force felt by a body on the surface that matters and either of the two would do that.
Or, as they do in many science fiction books, they just provide for a stronger, likely denser bone structure, that allows the natives to function at a much higher level of gravitation, say, 1.5 to 2.0 earth normal gravity.
No
I strongly believe there is or was life out there with a caveat:
Given the vastness of the universe, the chances of intelligent life appearing in two or more places at the same time must be extremely small and even if it did happen, the time to travel from the other planet to earth would be far too much to bother on the off chance that they could say “take me to your leader”.
Current understanding of the properties of the elements and the properties of many of the components of all living material is that there is no chance at all that unguided chance gave rise to life. The time from the beginning of there being atoms is far, far too short.
From Google’s AI bot as of this morning:
“As of March 2026, over 7,400 exoplanets have been confirmed, but ‘Earth-like’ planets—defined as rocky, Earth-sized worlds in a star’s habitable zone—are rare finds. While over 800 planets have radii less than 1.5 times Earth’s, only about 29 to 70+ are considered top candidates for potential habitability.
— Top Candidates: Prominent examples include Kepler-186f, Kepler-452b, and TRAPPIST-1e.
— Recent Discoveries: A recent study identified 45 rocky worlds deemed most likely to support life, acting as prime targets for future studies.
— Prevalence: Research suggests that roughly 10% of Sun-like stars possess a planet similar in size and light exposure to Earth.”
The problem is that planets around red dwarfs are probably not habitable.
Red dwarfs have frequent and very energetic solar storms and because of the low light output of red dwarfs, the “goldilocks zone” is quite close in.
As a result, any “habitable” planet has quite probably had it’s atmosphere stripped away long ago. Even if the planet has a magnetic field.
Please direct your “problem” to those scientific specialists in the search for exoplanets that are the ones defining “habitable” for the reset of us . . . that word did not originate with me.
If there are hundreds of habitable planets
and habitable planets would tend to develop life
and the universe is billions of years old
then
Where are the space travellers?
Commonly known as “Fermi’s Paradox” . . . check it out at
https://en.wikipedia.org/wiki/Fermi_paradox
with some speculative answers to the question.
Perhaps in stasis on ships that take millions of years to travers the void.
Perhaps in generation ships that … ditto…
There have been a lot of solar systems discovered. Very few have been “like ours”.
When I read these kind of things, I am reminded of the findings of the Voyager satellites when they learned so much about the outer planets. What was striking was how confident my childhood astronomy books were about composition, atmospheres and so forth about the outer planets and how wrong they were! It really makes me wonder how many major errors we have in our understanding of things that are really far away where so much depends on using physics and assumptions to get from actual measurements to conclusions and how thin our measurement data actually is.
Thanks for that.
The article describes how ratios isotopes of elements are the science. The rate at which isotopes shift is predictable. The original amount of the isotope in a material is conjecture.
If the ratios of isotopes of elements in two samples are the same, then maybe they were made in the same place. Or maybe they were made the same way at different places.
If the ratios of isotopes of elements in two samples are different, then maybe they were made in different places. Or maybe they were made differently in the same place.
eg: Are all Helium atoms in the sun the same age (where age is a determining factor in their isotope ratios?) If all Helium atoms in the sun are the same age, then what happens whn two Hydrogens fuse tomorrow morning?
Point of all this: They had to make assumptions. Maybe they made good assumptions.
Whew, lucked out.
Shortly after writing above I thought “waitaminit, does Helium have Isotopes?” Yes.
“Helium has two stable isotopes, Helium-3 and Helium-4 , with Helium-4 being by far the most abundant in nature, forming 99.999863% of natural helium. Several short-lived radioactive isotopes exist, including He-6 and He-8, which are studied in nuclear physics, with total isotopes ranging from He-3 up to He-10.”
You left out time. It is the decay of isotopes over time that leads to the estimates of age.
A proto-earth cleared its orbit and became massive enough to go-spherical.
Maybe I am supposed to be “truly astonished”, but I fail that tipping point.
Water is formed from H2 + O2 with an energy release in the formation.
Oxygen isotopes were traditionally used to identify source of matter in earth.
Hydrogen is so common and is a major part of the sun.
It can be considered a natural process that H2O formed while planets formed It does not drive a decision that H2O had to be imported.
It was long believed that the lighter molecules, were blown out of the inner solar system by the solar wind.
There are lots of things long believed that we are still investigating.
From the above article:
“This also implies that most volatile elements, such as water, must have already been present in the inner Solar System.”
Interesting comment in light of the on-going telescopic/spectroscopic searches for extrasolar planets that might accommodate some form of life.
To the best of my knowledge (and Web searches) the current exoplanet searches focus on detecting water vapor in exoplanet atmospheres or on the surfaces of planets, NOT in the solar material that is diffusely dispersed around the innermost part of the star’s planetary system.
Given the huge volume of the “inner portion” of a hypothesized planetary system compared to the volume hypothesized to exist in one or a few exoplanet atmospheres, the water vapor present “in space” in such cases should be easily detectable spectroscopically if it was really present in any significant amount despite being quite diffuse.
For example, according to Google’s AI bot:
“Water vapor has been detected in numerous interstellar clouds, spanning from stellar nurseries in our galaxy to distant, early-universe quasars. Observations from tools like the Infrared Space Observatory and the Herschel Space Observatory show water vapor is common in interstellar gas, with significant concentrations in warmer, denser regions.”
While water vapor has been detected in proximity to YOUNG stars and star-forming regions in space, Google’s AI bot has this to say about the presence of in-space water vapor for Sol:
“Sol (the Sun) is classified as a middle-aged star. At approximately 4.6 billion years old, it is currently in the stable “main sequence” phase of its life, which lasts for roughly 10 billion years . . . Water vapor is present in the space between the Sun and Mars, but not as a continuous, dense cloud. It exists in trace amounts, mainly as water molecules escaping from the Martian upper atmosphere due to solar ultraviolet radiation breaking apart water into hydrogen and oxygen.” (my bold emphasis added)
Furthermore, sunlight can dissociate water through photodissociation via ultraviolet (UV) radiation. UV rays split wter molecules into free radicals (H+ and OH-), which “solar wind” easily drive away from the inner portion of the solar system to the outer part of the solar system beyond which there is insufficient UV radiation flux to provide dissociation and prevent recombination.”
Bottom line: Yeah, Earth’s water MAY have arisen from materials originally present in proximity to an early Sol, but it is far from reasonable—even “proven”—that that hypothesized water content was present for the duration over which Earth consolidated into a solid and relatively “cool” planet.
IMHO, the theory of water-ice bearing comets bombarding solid Earth after its formation is still a viable explanation for Earth’s existing liquid water content, and it avoids the obvious problem of why Earth’s early climate, with surface temperatures during the Hadean Eon (approx. 4.5–4.0 billion years ago), averaging around 2,000°C, didn’t boil off all of Earth’s primordial water content.
It condensed when the Earth cooled, is one conjecture of many.
That would be “one heck of an atmosphere” that contained the equivalent of all of the world’s current liquid oceans as just water vapor way back then!
OK . . . it’s rightfully a “conjecture” . . . one having little appreciation for physics.
You are viewing the formation of the Earth as having happened after the sun. I’d guess they both happened simultaneously, and much of the Earth was already formed before the sun got bright and hot enough to generate the UV and solar wind that would prevent water molecules from remaining in the inner solar system. The water on Earth would be originally inside the surface, and protected until it was released by volcanic activity.
Which brings up my more puzzling question, where did the nitrogen in the atmospheres of the inner planets come from? Is it all from decay of carbon 14?
Best scientific estimate for the age of the Sun (Sol): 4.6 billion years
Best scientific estimate for the age of the Earth: 4.54 billion years, with a margin of error of plus or minus 1% (roughly plus/minus 50 million years).
FWIW, here is what Google’s AI bot states about this subject:
“Yes, the Sun existed before the Earth. The Sun formed approximately 4.6 billion years ago from a collapsing cloud of dust and gas, with most of this material forming the Sun first. The Earth and other planets accreted later from the remaining debris disk orbiting the new star.” (my bold emphasis added)
As for your last question, the presence of nitrogen in the atmospheres of the inner planets, as well as “metals” and heavy elements being present in their solid masses is strong evidence that the Sun is at least a third-generation (Population I) star.
Also from Google’s AI bot:
“The first generation of stars (Population III) formed from primordial hydrogen and helium, containing no heavier elements. They produced the first heavy elements, which were spread by supernova explosions. Second-generation stars (Population II) formed from this material, incorporating some heavy elements. The Sun, containing high amounts of elements heavier than helium (including nitrogen), formed from the remains of at least two previous generations of stars, making it a third-generation (or higher) star.
Origin of Nitrogen: Nitrogen is not formed during the Big Bang. It is produced through fusion inside stars—specifically in the CN cycle of CNO reactions. The nitrogen in our atmosphere and DNA was forged in the cores of earlier, massive stars that exploded and spread this material into the galaxy before our solar system was formed.”
Though my entire career was devoted to space, I am occasionally surprised by the magnitudes of certain things. This post made me wonder about the density of material in the pre-Earth solar system. Taking the mass of the Earth, and dividing it by the volume of a torus whose major radius is the semi-major axis of Earth’s orbit around the Sun, and whose minor radius is that the the Earth, gives a surprising result: 0.05 kg/m^3. The density of hydrogen gas at STP is 0.08988 kg/m^3! And assuming the mean atomic weight of the Earth is 26.5, the atomic number density of material in the torus is 4.4% that of air at sea level. Very wispy, yet still 17 orders of magnitude denser than the interplanetary medium today.
An old guess was mistaken, old explanations where unnecessary and irrelevant. Nothing new under the sun. Expect a significant amount of present theories called “scientific” to suffer the same fate. Wrong!
Scientific guesses (theories) are never settled and never immune from doubt and debate and further investigation. Someone tell this to mainstream media again, please.