Earth and Mars were formed from inner Solar System material

Earth and Mars were formed from material that largely originated in the inner Solar System; only a few percent of the building blocks of these two planets originated beyond Jupiter's orbit. A group of researchers led by the University of Münster (Germany) report these findings today in the journal Science Advances. They present the most comprehensive comparison to date of the isotopic composition of Earth, Mars and pristine building material from the inner and outer Solar System. Some of this material is today still found largely unaltered in meteorites. The results of the study have far-reaching consequences for our understanding of the process that formed the planets Mercury, Venus, Earth, and Mars. The theory postulating that the four rocky planets grew to their present size by accumulating millimeter-sized dust pebbles from the outer Solar System is not tenable.

Approximately 4.6 billion years ago in the early days of our Solar System, a disk of dust and gases orbited the young Sun. Two theories describe how in the course of millions of years the inner rocky planets formed from this original building material. According to the older theory, the dust in the inner Solar System agglomerated to ever larger chunks gradually reaching approximately the size of our Moon. Collisions of these planetary embryos finally produced the inner planets Mercury, Venus, Earth, and Mars. A newer theory, however, prefers a different growth process: millimeter-sized dust "pebbles" migrated from the outer Solar System towards the Sun. On their way, they were accreted onto the planetary embryos of the inner Solar System, and step by step enlarged them to their present size.

Both theories are based on theoretical models and computer simulations aimed at reconstructing the conditions and dynamics in the early Solar System; both describe a possible path of planet formation. But which one is right? Which process actually took place? To answer these questions, in their current study researchers from the University of Münster (Germany), the Observatoire de la Cote d'Azur (France), the California Institute of Technology (USA), the Natural History Museum Berlin (Germany), and the Free University of Berlin (Germany) determined the exact composition of the rocky planets Earth and Mars. "We wanted to find out whether the building blocks of Earth and Mars originated in the outer or inner Solar System," says Dr. Christoph Burkhardt of the University of Münster, the study's first author. To this end, the isotopes of the rare metals titanium, zirconium and molybdenum found in minute traces in the outer, silicate-rich layers of both planets provide crucial clues. Isotopes are different varieties of the same element, which differ only in the weight of their atomic nucleus.

Meteorites as a reference

Scientists assume that in the early Solar System these and other metal isotopes were not evenly distributed. Rather, their abundance depended on the distance from the Sun. They therefore hold valuable information about where in the early Solar System a certain body's building blocks originated.

As a reference for the original isotopic inventory of the outer and inner Solar System, the researchers used two types of meteorites. These chunks of rock generally found their way to Earth from the asteroid belt, the region between the orbits of Mars and Jupiter. They are considered to be largely pristine material from the beginnings of the Solar System. While so-called carbonaceous chondrites, which can contain up to a few percent carbon, originated beyond Jupiter's orbit and only later relocated to the asteroid belt due to influence of the growing gas giants, their more carbon-depleted cousins, the non-carbonaceous chondrites, are true children of the inner Solar System.

The precise isotopic composition of Earth's accessible outer rock layers and that of both types of meteorites have been studied for some time; however, there have been no comparably comprehensive analyses of Martian rocks. In their current study, the researchers now examined samples from a total of 17 Martian meteorites, which can be assigned to six typical types of Martian rock. In addition, the scientists for the first time investigated the abundances of three different metal isotopes.

The samples of Martian meteorites were first powdered and subjected to complex chemical pretreatment. Using a multicollector plasma mass spectrometer at the Institute of Planetology at the University of Münster, the researchers were then able to detect tiny amounts of titanium, zirconium, and molybdenum isotopes. They then performed computer simulations to calculate the ratio in which building material found today in carbonaceous and non-carbonaceous chondrites must have been incorporated into Earth and Mars in order to reproduce their measured compositions. In doing so, they considered two different phases of accretion to account for the different history of the titanium and zirconium isotopes as well as of the molybdenum isotopes, respectively. Unlike titanium and zirconium, molybdenum accumulates mainly in the metallic planetary core. The tiny amounts still found today in the silicate-rich outer layers can therefore only have been added during the very last phase of the planet's growth.

The researchers' results show that the outer rock layers of Earth and Mars have little in common with the carbonaceous chondrites of the outer Solar System. They account for only about four percent of both planets' original building blocks. "If early Earth and Mars had mainly accreted dust grains from the outer Solar System, this value should be almost ten times higher," says Prof. Dr. Thorsten Kleine of the University of Münster, who is also director at the Max Planck Institute for Solar System Research in Göttingen. "We thus cannot confirm this theory of the formation of the inner planets," he adds.

Lost building material

But the composition of Earth and Mars does not exactly match the material of the non-carbonaceous chondrites either. The computer simulations suggest that another, different kind of building material must also have been in play. "The isotopic composition of this third type of building material as inferred by our computer simulations implies it must have originated in the innermost region of the Solar System," explains Christoph Burkhardt. Since bodies from such close proximity to the Sun were almost never scattered into the asteroid belt, this material was almost completely absorbed into the inner planets and thus does not occur in meteorites. "It is, so to speak, 'lost building material' to which we no longer have direct access today," says Thorsten Kleine.

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Radioactive radiation could damage biological tissue also via a previously unnoticed mechanism

When cells are exposed to ionizing radiation, more destructive chain reactions may occur than previously thought. An international team led by researchers from the Max Planck Institute for Nuclear Physics in Heidelberg has for the first time observed intermolecular Coulombic decay in organic molecules. This is triggered by ionizing radiation such as from radioactivity or from space. The effect damages two neighbouring molecules and ultimately leads to the breaking of bonds -- like the ones in DNA and proteins. The finding not only improves the understanding of radiation damage but could also help in the search for more effective substances to support radiation therapy.

Sometimes radioactive damage cannot be great enough -- especially when it comes to destroying tumour tissue with ionizing radiation. In radiation therapy, substances that specifically enhance the damage of the radiation in the tumour tissue are used. "The intermolecular Coulombic decay we found could help make such sensitizers more effective," says Alexander Dorn, who heads a research group at the Max Planck Institute for Nuclear Physics and was instrumental in the current study. His team's observations could also improve our understanding of how artificial or natural ionizing radiation damages the genetic material of healthy tissue.

Excess energy leads to a Coulomb explosion

The DNA double helix of the genome resembles a rope ladder with rungs of nucleic base pairs. "Because experiments with the free nucleic bases are difficult, we initially studied pairs of benzene molecules as a model system," explains Dorn. These hydrocarbon rings are connected in a similar way to the nucleic bases stacked on top of each other in a strand of DNA. The researchers bombarded the benzene pairs with electrons, thereby imitating radioactive radiation to a certain extent. When an electron hit a benzene molecule, it was ionized and charged with a lot of energy. The team has now observed that the molecule transferred some of this energy to its partner molecule. This energy boost was enough to ionize the second molecule as well. Both molecules were thus positively charged. Of course, that didn't last long. The two molecular ions repelled each other and flew apart in a Coulomb explosion.

Until now, scientists had assumed that ionizing radiation damages biomolecules mainly indirectly. The high-energy radiation also ionizes the water of which a cell is largely composed and which surrounds biomolecules such as DNA. The ionized water molecules -- especially hydroxide ions -- then attack the DNA. And if an electron of the beta radiation or a gamma quantum does hit a DNA molecule directly, the excess energy normally is dissipated by processes in the molecule itself. It thus remains intact. Or at least that was the assumption up to now. In any case, the weak bonds between different molecules or different parts of the molecule -- as they exist in DNA and proteins -- should not be affected by this either. However, in their reaction microscope, the researchers observed that radioactive radiation can indeed break such bonds. This instrument allows them not only to detect the two separating benzene molecules and measure their energy but also to characterize the electrons emitted.

Fatal consequences of multiple DNA breaks

"It is not yet clear how the intermolecular Coulombic decay affects the DNA strand," says Dorn. If a single strand in the DNA ladder breaks, the consequences should not be too serious. However, the mechanism observed also releases several electrons that can "blow up" further pairs of molecules. And if both strands of DNA are broken in the immediate vicinity, this could have fatal consequences.

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‘Battle of the sexes’ begins in womb as father and mother’s genes tussle over nutrition

Cambridge scientists have identified a key signal that the fetus uses to control its supply of nutrients from the placenta, revealing a tug-of-war between genes inherited from the father and from the mother. The study, carried out in mice, could help explain why some babies grow poorly in the womb.

As the fetus grows, it needs to communicate its increasing needs for food to the mother. It receives its nourishment via blood vessels in the placenta, a specialised organ that contains cells from both baby and mother.

Between 10% and 15% of babies grow poorly in the womb, often showing reduced growth of blood vessels in the placenta. In humans, these blood vessels expand dramatically between mid and late gestation, reaching a total length of approximately 320 kilometres at term.

In a study published today in Developmental Cell, a team led by scientists at the University of Cambridge used genetically engineered mice to show how the fetus produces a signal to encourage growth of blood vessels within the placenta. This signal also causes modifications to other cells of the placenta to allow for more nutrients from the mother to go through to the fetus.

Dr Ionel Sandovici, the paper's first author, said: "As it grows in the womb, the fetus needs food from its mum, and healthy blood vessels in the placenta are essential to help it get the correct amount of nutrients it needs.

"We've identified one way that the fetus uses to communicate with the placenta to prompt the correct expansion of these blood vessels. When this communication breaks down, the blood vessels don't develop properly and the baby will struggle to get all the food it needs."

The team found that the fetus sends a signal known as IGF2 that reaches the placenta through the umbilical cord. In humans, levels of IGF2 in the umbilical cord progressively increase between 29 weeks of gestation and term: too much IGF2 is associated with too much growth, while not enough IGF2 is associated with too little growth. Babies that are too large or too small are more likely to suffer or even die at birth, and have a higher risk to develop diabetes and heart problems as adults.

Dr Sandovici added: "We've known for some time that IGF2 promotes the growth of the organs where it is produced. In this study, we've shown that IGF2 also acts like a classical hormone -- it's produced by the fetus, goes into the fetal blood, through the umbilical cord and to the placenta, where it acts."

Particularly interesting is what their findings reveal about the tussle taking place in the womb.

In mice, the response to IGF2 in the blood vessels of the placenta is mediated by another protein, called IGF2R. The two genes that produce IGF2 and IGF2R are 'imprinted' -- a process by which molecular switches on the genes identify their parental origin and can turn the genes on or off. In this case, only the copy of the igf2 gene inherited from the father is active, while only the copy of igf2r inherited from the mother is active.

Lead author Dr Miguel Constância, said: "One theory about imprinted genes is that paternally-expressed genes are greedy and selfish. They want to extract the most resources as possible from the mother. But maternally-expressed genes act as countermeasures to balance these demands."

"In our study, the father's gene drives the fetus's demands for larger blood vessels and more nutrients, while the mother's gene in the placenta tries to control how much nourishment she provides. There's a tug-of-war taking place, a battle of the sexes at the level of the genome."

The team say their findings will allow a better understanding of how the fetus, placenta and mother communicate with each other during pregnancy. This in turn could lead to ways of measuring levels of IGF2 in the fetus and finding ways to use medication to normalise these levels or promote normal development of placental vasculature.

The researchers used mice, as it is possible to manipulate their genes to mimic different developmental conditions. This enables them to study in detail the different mechanisms taking place. The physiology and biology of mice have many similarities with those of humans, allowing researchers to model human pregnancy, in order to understand it better.

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Contorted oceanic plate caused complex quake off New Zealand’s East Cape

Subduction zones, where a slab of oceanic plate is pushed beneath another tectonic plate down into the mantle, cause the world's largest and most destructive earthquakes. Reconstructing the geometry and stress conditions of the subducted slabs at subduction zones is crucial to understanding and preparing for major earthquakes. However, the tremendous depths of these slabs make this challenging -- seismologists rely mainly on the rare windows into these deeply buried slabs provided by the infrequent but strong earthquakes, termed intraslab earthquakes, that occur within them.

In a new study published in Geophysical Research Letters, a research team led by the University of Tsukuba used seismic data generated by a magnitude 7.3 earthquake that occurred off the northeasternmost tip of New Zealand's North Island on March 4, 2021, detected by seismometers around the world, to investigate the particularly unusual geometry and stress states of the subducted slab deep below the surface in this region.

"The 2021 East Cape earthquake showed a complex rupture process, likely because of its location at the boundary between the Kermadec Trench to the north and the Hikurangi Margin to the south," lead author of the study Assistant Professor Ryo Okuwaki explains. "To investigate the geometry of the stress field and earthquake rupture process, we used a novel finite-fault inversion technique that required no pre-existing knowledge of the area's faults."

This investigation revealed multiple episodes of rupture, generated by both compression and extension in the subsurface at different depths. These episodes included shallow (~30 km) rupture due to extension perpendicular to the trench as would typically be expected in a subduction zone. Unexpectedly, however, the deep (~70 km) rupture occurred with compression parallel to the subduction trench.

"Two alternative or inter-related factors may explain the unique rupture geometry of the 2021 East Cape earthquake," senior author Professor Yuji Yagi explains. "First, subduction of a seamount or multiple seamounts along with the subducted slab could contort the slab and create local changes in the stress field. Second, the transition from the Kermadec Trench to the Hikurangi Margin, where the subducted oceanic crust is considerably thicker, could create the local conditions responsible for the unusual faulting pattern."

Because of the rarity of deep intraslab earthquakes in this region, distinguishing between these two possibilities is currently challenging, and indeed both factors might play significant roles in creating the complex stress field revealed by the East Cape earthquake. Additional earthquakes off the northeast coast of New Zealand in the future may shed further light on this deep tectonic mystery.

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NASA's Webb telescope launches to see first galaxies, distant worlds

NASA's James Webb Space Telescope launched at 7:20 a.m. EST Saturday on an Ariane 5 rocket from Europe's Spaceport in French Guiana, South America.

A joint effort with ESA (European Space Agency) and the Canadian Space Agency, the Webb observatory is NASA's revolutionary flagship mission to seek the light from the first galaxies in the early universe and to explore our own solar system, as well as planets orbiting other stars, called exoplanets.

"The James Webb Space Telescope represents the ambition that NASA and our partners maintain to propel us forward into the future," said NASA Administrator Bill Nelson. "The promise of Webb is not what we know we will discover; it's what we don't yet understand or can't yet fathom about our universe. I can't wait to see what it uncovers!"

Ground teams began receiving telemetry data from Webb about five minutes after launch. The Arianespace Ariane 5 rocket performed as expected, separating from the observatory 27 minutes into the flight. The observatory was released at an altitude of approximately 75 miles (120 kilometers). Approximately 30 minutes after launch, Webb unfolded its solar array, and mission managers confirmed that the solar array was providing power to the observatory. After solar array deployment, mission operators will establish a communications link with the observatory via the Malindi ground station in Kenya, and ground control at the Space Telescope Science Institute in Baltimore will send the first commands to the spacecraft.

Engineers and ground controllers will conduct the first of three mid-course correction burns about 12 hours and 30 minutes after launch, firing Webb's thrusters to maneuver the spacecraft on an optimal trajectory toward its destination in orbit about 1 million miles from Earth.

"I want to congratulate the team on this incredible achievement -- Webb's launch marks a significant moment not only for NASA, but for thousands of people worldwide who dedicated their time and talent to this mission over the years," said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. "Webb's scientific promise is now closer than it ever has been. We are poised on the edge of a truly exciting time of discovery, of things we've never before seen or imagined."

The world's largest and most complex space science observatory will now begin six months of commissioning in space. At the end of commissioning, Webb will deliver its first images. Webb carries four state-of-the-art science instruments with highly sensitive infrared detectors of unprecedented resolution. Webb will study infrared light from celestial objects with much greater clarity than ever before. The premier mission is the scientific successor to NASA's iconic Hubble and Spitzer space telescopes, built to complement and further the scientific discoveries of these and other missions.

"The launch of the Webb Space Telescope is a pivotal moment -- this is just the beginning for the Webb mission," said Gregory L. Robinson, Webb's program director at NASA Headquarters. "Now we will watch Webb's highly anticipated and critical 29 days on the edge. When the spacecraft unfurls in space, Webb will undergo the most difficult and complex deployment sequence ever attempted in space. Once commissioning is complete, we will see awe-inspiring images that will capture our imagination."

The telescope's revolutionary technology will explore every phase of cosmic history -- from within our solar system to the most distant observable galaxies in the early universe, to everything in between. Webb will reveal new and unexpected discoveries and help humanity understand the origins of the universe and our place in it.

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Computer simulation models potential asteroid collisions

An asteroid impact can be enough to ruin anyone's day, but several small factors can make the difference between an out-of-this-world story and total annihilation. In AIP Advances, by AIP Publishing, a researcher from the National Institute of Natural Hazards in China developed a computer simulation of asteroid collisions to better understand these factors.

The computer simulation initially sought to replicate model asteroid strikes performed in a laboratory. After verifying the accuracy of the simulation, Duoxing Yang believes it could be used to predict the result of future asteroid impacts or to learn more about past impacts by studying their craters.

"From these models, we learn generally a destructive impact process, and its crater formation," said Yang. "And from crater morphologies, we could learn impact environment temperatures and its velocity."

Yang's simulation was built using the space-time conservation element and solution element method, designed by NASA and used by many universities and government agencies, to model shock waves and other acoustic problems.

The goal was to simulate a small rocky asteroid striking a larger metal asteroid at several thousand meters per second. Using his simulation, Yang was able to calculate the effects this would have on the metal asteroid, such as the size and shape of the crater.

The simulation results were compared against mock asteroid impacts created experimentally in a laboratory. The simulation held up against these experimental tests, which means the next step in the research is to use the simulation to generate more data that can't be produced in the laboratory.

This data is being created in preparation for NASA's Psyche mission, which aims to be the first spacecraft to explore an asteroid made entirely of metal. Unlike more familiar rocky asteroids, which are made of roughly the same materials as the Earth's crust, metal asteroids are made of materials found in the Earth's inner core. NASA believes studying such an asteroid can reveal more about the conditions found in the center of our own planet.

Yang believes computer simulation models can generalize his results to all metal asteroid impacts and, in the process, answer several existing questions about asteroid interactions.

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Astronomers capture black hole eruption spanning 16 times the full Moon in the sky

Astronomers have produced the most comprehensive image of radio emission from the nearest actively feeding supermassive black hole to Earth.

The emission is powered by a central black hole in the galaxy Centaurus A, about 12 million light years away.

As the black hole feeds on in-falling gas, it ejects material at near light-speed, causing 'radio bubbles' to grow over hundreds of millions of years.

When viewed from Earth, the eruption from Centaurus A now extends eight degrees across the sky -- the length of 16 full Moons laid side by side.

It was captured using the Murchison Widefield Array (MWA) telescope in outback Western Australia.

The research was published today in the journal Nature Astronomy.

Lead author Dr Benjamin McKinley, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said the image reveals spectacular new details of the radio emission from the galaxy.

"These radio waves come from material being sucked into the supermassive black hole in the middle of the galaxy," he said.

"It forms a disc around the black hole, and as the matter gets ripped apart going close to the black hole, powerful jets form on either side of the disc, ejecting most of the material back out into space, to distances of probably more than a million light years.

"Previous radio observations could not handle the extreme brightness of the jets and details of the larger area surrounding the galaxy were distorted, but our new image overcomes these limitations."

Centaurus A is the closest radio galaxy to our own Milky Way.

"We can learn a lot from Centaurus A in particular, just because it is so close and we can see it in such detail," Dr McKinley said.

"Not just at radio wavelengths, but at all other wavelengths of light as well.

"In this research we've been able to combine the radio observations with optical and x-ray data, to help us better understand the physics of these supermassive black holes."

Astrophysicist Dr Massimo Gaspari, from Italy's National Institute for Astrophysics, said the study corroborated a novel theory known as 'Chaotic Cold Accretion' (CCA), which is emerging in different fields.

"In this model, clouds of cold gas condense in the galactic halo and rain down onto the central regions, feeding the supermassive black hole," he said.

"Triggered by this rain, the black hole vigorously reacts by launching energy back via radio jets that inflate the spectacular lobes we see in the MWA image. This study is one of the first to probe in such detail the multiphase CCA 'weather' over the full range of scales," Dr Gaspari concluded.

Dr McKinley said the galaxy appears brighter in the centre where it is more active and there is a lot of energy.

"Then it's fainter as you go out because the energy's been lost and things have settled down," he said.

"But there are interesting features where charged particles have re-accelerated and are interacting with strong magnetic fields."

MWA director Professor Steven Tingay said the research was possible because of the telescope's extremely wide field-of-view, superb radio-quiet location, and excellent sensitivity.

"The MWA is a precursor for the Square Kilometre Array (SKA) -- a global initiative to build the world's largest radio telescopes in Western Australia and South Africa," he said.

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1,500 endangered languages at high risk of being lost this century

A world-first study warns 1,500 endangered languages could no longer be spoken by the end of this century.

The study, led by The Australian National University (ANU), identified predictors that put endangered languages at high risk.

Co-author Professor Lindell Bromham said that of the world's 7,000 recognised languages, around half were currently endangered.

"We found that without immediate intervention, language loss could triple in the next 40 years. And by the end of this century, 1,500 languages could cease to be spoken."

Published in Nature Ecology and Evolution, they study charts the widest range of factors ever putting endangered languages under pressure.

One finding was that more years of schooling increased the level of language endangerment. The researchers say it shows we need to build curricula that support bilingual education, fostering both indigenous language proficiency as well as use of regionally-dominant languages.

"Across the 51 factors or predictors we investigated, we also found some really unexpected and surprising pressure points. This included road density," Professor Bromham said.

"Contact with other local languages is not the problem -- in fact languages in contact with many other Indigenous languages tend to be less endangered.

"But we found that the more roads there are, connecting country to city, and villages to towns, the higher the risk of languages being endangered. It's as if roads are helping dominant languages 'steam roll' over other smaller languages."

The researchers say the findings also have important lessons for preserving many of the endangered languages spoken by Australia's First Nations peoples.

"Australia has the dubious distinction of having one of the highest rates of language loss worldwide," Professor Felicity Meakins, from the University of Queensland and one of the study's co-authors, said.

"Prior to colonisation, more than 250 First Nations languages were spoken, and multilingualism was the norm. Now, only 40 languages are still spoken and just 12 are being learnt by children.

"First Nations languages need funding and support. Australia only spends $20.89 annually per capita of the Indigenous population on languages, which is abysmal compared with Canada's $69.30 and New Zealand's $296.44."

Professor Bromham said that as the world enters the UNESCO Decade of Indigenous Languages in 2022, the study's findings were a vital reminder that more action was urgently needed to preserve at-risk languages.

"When a language is lost, or is 'Sleeping' as we say for languages that are no longer spoken, we lose so much of our human cultural diversity. Every language is brilliant in its own way.

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Solar flare throws light on ancient trade between the Islamic Middle East and the Viking Age

Mobility shaped the human world profoundly long before the modern age. But archaeologists often struggle to create a timeline for the speed and impact of this mobility. An interdisciplinary team of researchers at the Danish National Research Foundation's Centre for Urban Network Evolutions at Aarhus University (UrbNet) has now made a breakthrough by applying new astronomical knowledge about the past activity of the sun to establish an exact time anchor for global links in the year 775 CE.

In collaboration with the Museum of Southwest Jutland in the Northern Emporium Project, the team has conducted a major excavation at Ribe, one of Viking-age Scandinavia's principal trading towns. Funded by the Carlsberg Foundation, the dig and the subsequent research project were able to establish the exact sequence of the arrival of objects from various corners of the world at the market in Ribe. In this way, they were able to trace the emergence of the vast network of Viking-age trade connections with regions such as North Atlantic Norway, Frankish Western Europe and the Middle East. To obtain a chronology for these events, the team has pioneered a new use of radiocarbon dating.

New use of radiocarbon dating

"The applicability of radiocarbon dating has hitherto been limited due to the broad age ranges of this method. Recently, however, it has been discovered that solar particle events, also known as Miyake events, cause sharp spikes in atmospheric radiocarbon for a single year. They are named after the female Japanese researcher Fusa Miyake, who first identified these events in 2012. When these spikes are identified in detailed records such as tree rings or in an archaeological sequence, it reduces the uncertainty margins considerably," says lead author Bente Philippsen.

The team applied a new, improved calibration curve, based on annual samples, to identify a 775 CE Miyake event in one floor layer in Ribe. This enabled the team to anchor the entire sequence of layers and 140 radiocarbon dates around this single year.

"This result shows that the expansion of Afro-Eurasian trade networks, characterised by the arrival of large numbers of Middle Eastern beads, can be dated in Ribe with precision to 790±10 CE -- coinciding with the beginning of the Viking Age. However, imports brought by ship from Norway were arriving as early as 750 CE," says Professor Søren Sindbæk, who is also a member of the team.

This groundbreaking result challenges one of the most widely accepted explanations for maritime expansions in the Viking Age -- that Scandinavian seafaring took off in response to growing trade with the Middle East through Russia. Maritime networks and long-distance trade were already established decades before impulses from the Middle East caused a further expansion of these networks.

The construction of the new, annual calibration curve is a global effort to which the researchers from UrbNet and the Aarhus AMS Centre at the Department of Physics and Astronomy at Aarhus University have contributed.

"The construction of a calibration curve is a huge international effort with contributions from many laboratories around the world. Fusa Miyake's discovery in 2012 has revolutionized our work, so that we now work with annual time resolution. New calibration curves are recurrently released, most recently in 2020, and Aarhus AMS centre has contributed significantly. The new high-resolution data from the present study will enter into a future update of the calibration curve and thus contribute to improve the precision of archaeological dates worldwide. This will provide better opportunities to understand rapid developments such as trade flows or environmental change in the past," says Jesper Olsen, Associate Professor at Aarhus AMS Centre.

The global trends revealed by the study are essential for the archaeology of trading towns like Ribe. "The new results enable us to date the influx of new artefacts and far-reaching contacts on a much better background. This will help us to visualise and describe Viking Age Ribe in a way that will have great value for scientists, as well as helping us to present the new insight to the general public," says Claus Feveile, curator of the Museum of Southwest Jutland.

Background facts

One of the most spectacular episodes of pre-modern global connectivity happened in the period c. 750-1000 CE, when trade with the burgeoning Islamic empire in the Middle East connected virtually all corners of Afro-Eurasia.

The spread of coins, trade beads and other exotic artefacts provides archaeological evidence of the trade links stretching from Southeast Asia and Africa to Siberia and the northernmost corners of Scandinavia. In the north, these long-distance connections mark the beginning of the maritime adventures that define the Viking Age. Researchers have even suggested that it was the arrival of silver and other valuable objects via Eastern Europe which sparked the first Scandinavian Viking expeditions.

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70 new rogue planets discovered in our galaxy

Rogue planets are elusive cosmic objects that have masses comparable to those of the planets in our Solar System but do not orbit a star, instead roaming freely on their own. Not many were known until now, but a team of astronomers, using data from several European Southern Observatory (ESO) telescopes and other facilities, have just discovered at least 70 new rogue planets in our galaxy. This is the largest group of rogue planets ever discovered, an important step towards understanding the origins and features of these mysterious galactic nomads.

"We did not know how many to expect and are excited to have found so many," says Núria Miret-Roig, an astronomer at the Laboratoire d'Astrophysique de Bordeaux, France and the University of Vienna, Austria, and the first author of the new study published today in Nature Astronomy.

Rogue planets, lurking far away from any star illuminating them, would normally be impossible to image. However, Miret-Roig and her team took advantage of the fact that, in the few million years after their formation, these planets are still hot enough to glow, making them directly detectable by sensitive cameras on large telescopes. They found at least 70 new rogue planets with masses comparable to Jupiter's in a star-forming region close to our Sun, in the Upper Scorpius and Ophiuchus constellations.

To spot so many rogue planets, the team used data spanning about 20 years from a number of telescopes on the ground and in space. "We measured the tiny motions, the colours and luminosities of tens of millions of sources in a large area of the sky," explains Miret-Roig. "These measurements allowed us to securely identify the faintest objects in this region, the rogue planets."

The team used observations from ESO's Very Large Telescope (VLT), the Visible and Infrared Survey Telescope for Astronomy (VISTA), the VLT Survey Telescope (VST) and the MPG/ESO 2.2-metre telescope located in Chile, along with other facilities. "The vast majority of our data come from ESO observatories, which were absolutely critical for this study. Their wide field of view and unique sensitivity were keys to our success," explains Hervé Bouy, an astronomer at the Laboratoire d'Astrophysique de Bordeaux, France, and project leader of the new research. "We used tens of thousands of wide-field images from ESO facilities, corresponding to hundreds of hours of observations, and literally tens of terabytes of data."

The team also used data from the European Space Agency's Gaia satellite, marking a huge success for the collaboration of ground- and space-based telescopes in the exploration and understanding of our Universe.

The study suggests there could be many more of these elusive, starless planets that we have yet to discover. "There could be several billions of these free-floating giant planets roaming freely in the Milky Way without a host star," Bouy explains.

By studying the newly found rogue planets, astronomers may find clues to how these mysterious objects form. Some scientists believe rogue planets can form from the collapse of a gas cloud that is too small to lead to the formation of a star, or that they could have been kicked out from their parent system. But which mechanism is more likely remains unknown.

Further advances in technology will be key to unlocking the mystery of these nomadic planets. The team hopes to continue to study them in greater detail with ESO's forthcoming Extremely Large Telescope (ELT), currently under construction in the Chilean Atacama Desert and due to start observations later this decade. "These objects are extremely faint and little can be done to study them with current facilities," says Bouy. "The ELT will be absolutely crucial to gathering more information about most of the rogue planets we have found."

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