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Stars from ancient cluster found in the Milky Way

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Enlarge / Scientists have used the data from Gaia to track the location and motion of stars in our galaxy.

Galaxies like the Milky Way are thought to have been built through a series of mergers, drawing in smaller galaxies and clusters of stars and making these foreign stars their own. In some cases, the mergers were recent enough that we can still detect the formerly independent object as a cluster of stars orbiting the Milky Way together. But, as time goes on, interactions with the rest of the stars in the Milky Way will slowly disrupt any structures the cluster incorporates.

So it’s a bit of a surprise that researchers found what appear to be the remains of a globular cluster composed of some of the oldest stars around. The finding is consistent with a “growth through merger” model of galaxy construction, but it raises questions about how the cluster stayed intact for as long as it did.

Data-mining Gaia

The results started with an analysis of data from the ESA’s Gaia mission, which set out to do nothing less than map the Milky Way in three dimensions. Gaia imaged roughly a billion objects dozens of times, enough to estimate both their location and their motion around the Milky Way’s core. This map has helped scientists identify structures within our galaxy based on the fact that there are some groups of stars that are not only physically close to each other, but all moving in the same direction.

The process of mining the Gaia data for these sorts of structures is so useful that there’s a software algorithm called STREAMFINDER that identifies them. That software led to the discovery of the C-19 stellar stream, a group of stars moving together through the Milky Way’s halo.

One way to check whether these groups of stars really started out as part of a single cluster is to check their age; clusters are often composed of stars with similar ages. One of the ways to see if stars formed at the same time is to check the content of heavier elements. There was little in the way of elements heavier than helium formed during the Big Bang, so most heavy elements that are now present were produced by earlier stars. The later in the history of the Universe a star formed, the more of these heavier elements that star is likely to contain.

(Astronomers call any element heavier than helium a metal and refer to a star’s heavy-element content as its metallicity. But this will probably confuse most non-astronomers, so we’ll avoid it.)

So, the astronomers behind the new work measured the levels of heavy elements in the stars that were thought to belong to the C-19 stream. And, with the exception of one outlier, they were all quite similar, suggesting that the stream really is the disrupted remnant of a cluster. But the results also contained a surprise: a remarkably low amount of heavy elements.

Ancient history

The typical way of registering heavy elements is through the ratio of iron (which is only formed late in the life of massive star) to hydrogen. Hydrogen has always been the most abundant element in the Universe, while iron levels have slowly built over time. So the higher the iron-to-hydrogen ratio, the more recently the star formed.

In the case of the C-19 stream, the ratio was extremely low. So low, that the stars of C-19 would have formed prior to 3 billion years after the Big Bang, or when the Universe was only about a quarter of its current age. And they likely formed quite a bit earlier than that.

Within the Milky Way, a few hundred stars have been identified with similarly low heavy-element levels. But no cluster in which every star has such a low level has ever been seen. In fact, prior to this discovery, clusters in the Milky Way were thought to have a heavy-element floor—all of them had levels above those seen in the C-19 stream. This was true despite the fact that, based on the distribution of known clusters, we’d expect about five with heavy-element levels similar to that of the C-19 stream.

The lack of other clusters suggests that most of the earliest clusters like this stream have already been disrupted to the point that they’ve faded into the background of Milky Way stars. Which raises the question of why the C-19 stream hasn’t. That’s especially unexpected given that the stream’s orbit around the galactic core takes it deep inside the Milky Way, giving it plenty of chances to engage in interactions with other features that should disrupt it.

One possibility that could explain this is that the cluster originally entered the Milky Way as part of a dwarf galaxy that was swallowed. The dwarf galaxy’s structure could provide a degree of protection until it became disrupted and its stars spread through the Milky Way. And, if this were true, then the cluster that gave rise to the C-19 stream would have had a large fraction of the stars present in the dwarf galaxy at the time.

Regardless of how it ends up being explained, the presence of the C-19 stream tells us things about the history of the Universe. “The very existence of C-19 proves that globular clusters must have been able to form in the lowest-metallicity environments as the first galactic structures were assembling,” the researchers conclude.

Nature, 2022. DOI: 10.1038/s41586-021-04162-2  (About DOIs).

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A crab’s-eye view of the ancient world

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The fossil crab Callichimaera perplexa. Credit: Daniel Ocampo R. / Vencejo Films

Their legs may get more attention, but a new study says a crab’s eyes have much to offer, too—at least scientifically.

Writing in the journal iScience, paleontologists from Yale and Harvard have discovered new, unusually large optical features from a 95-million-year-old crab fossil, Callichimaera perplexa—a species first described in 2019 in a study led by former Yale paleontologist Javier Luque—which suggest that Callichimaera was a predator.

Callichimaera, which was found in Boyacá, Colombia, and Wyoming, in the United States, was about the size of a quarter, featuring large compound eyes with no sockets, bent claws, leg-like mouth parts, an exposed tail, and a long body. Previous research indicated that it was the earliest example of a swimming arthropod with paddle-like legs since the extinction of sea scorpions more than 250 million years ago.

“The specimens we have of the unusual Cretaceous crab Callichimaera perplexa preserve some very delicate eye tissues that don’t normally preserve,” said Kelsey Jenkins, a graduate student in Earth & Planetary Sciences at Yale and the new study’s first author. “This includes things like facets and internal optical tissues. This kind of excellent preservation is rare.”

The co-corresponding author of the study is Luque, who is now a research associate at Harvard. The study’s co-author is Derek Briggs, the G. Evelyn Hutchinson Professor of Earth & Planetary Sciences in Yale’s Faculty of Arts and Sciences. Briggs is also curator of invertebrate paleontology at the Yale Peabody Museum of Natural History.

Lead author Kelsey Jenkins studying extant crabs at the Yale Peabody Museum. Credit: Yale University

For the study, the researchers analyzed nearly 1,000 living crabs and fossils, including crabs at different stages of development, representing 15 crab species. The researchers compared the size of the crabs’ eyes and how fast they grew.

Callichimaera topped the list in both categories. Its eyes were about 16% of its body size.

“I’m 5’2.” If my eyes were this big, they’d be a little over 9 inches in diameter,” Jenkins said. “If something has eyes this big, they’re definitely very highly visual. This is in stark contrast to crabs with tiny, vestigial eyes where they may only be 1 to 3% of the animal’s body size.”

Likewise, Callichimaera’s optical growth rate was faster than any other crab the researchers studied. “Crabs whose eyes are growing very quickly are more visually inclined—likely they’re very good predators who use their eyes when hunting—whereas slow-growing eyes tend to be found in scavenger crabs that are less visually reliant,” Briggs said.

Tellingly, it was a fresh set of eyes that made the latest Callichimaera finding possible. Jenkins, whose main research experience has been with reptiles, wanted to learn more about another type of animal—hence, crabs.

“Javier and Derek mentored me, and I was able to provide an outsider’s perspective on a group of animals I was originally unfamiliar with,” Jenkins said.

Meet Callichimaera perplexa, the platypus of crabs

More information:
Kelsey M. Jenkins et al, The remarkable visual system of a Cretaceous crab, iScience (2021). DOI: 10.1016/j.isci.2021.103579
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Yale University

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‘Truly remarkable’ fossil is rare evidence of ancient shark-on-shark attacks

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This illustration, depicting an active predatory encounter between two requiem sharks off what is now the coast of Maryland, shows one possible way the shark vertebra could have been bitten.  (Image credit: Original drawing by Tim Scheirer; Coloration added by Clarence Schumaker; CC BY 4.0)

During the age of megalodon, sharks hunted all kinds of creatures, including other sharks, according to a new study based on four rare fossils.

In four separate finds, researchers and amateur fossil hunters discovered the ancient vertebrae of now-extinct sharks; all four vertebrae are covered in shark bite marks, and two still have pointy shark teeth sticking out of them. These findings are extraordinary, as shark skeletons are made of cartilage, which doesn’t fossilize well, the researchers said. 

The discoveries show that millions of years ago, ancient sharks gobbled up fellow sharks off what is now the U.S. East Coast. “Sharks have been preying upon each other for millions of years, yet these interactions are rarely reported due to the poor preservation potential of cartilage,” study co-researcher Victor Perez, an assistant curator of paleontology at the Calvert Marine Museum in Solomons, Maryland, told Live Science in an email.

Related: 7 unanswered questions about sharks

Researchers have known for decades about shark-on-shark predation and even cannibalism. It’s a behavior seen in living sharks, including many lamniformes — an iconic group that includes goblin, megamouth, basking, mako and great white sharks — which, as fetuses, sometimes devour their siblings in the womb, the researchers said.

Ancient sharks have left their bite marks on countless paleo beasts, including on the bones of marine mammals, ray-finned fishes and reptiles — even pterosaurs, flying reptiles that lived during the dinosaur age, two studies found. However, evidence of ancient shark-versus-shark attacks is somewhat rare. The oldest evidence of shark-on-shark predation dates to the Devonian period (419.2 million to 358.9 million years ago), when the shark Cladoselache gulped down another shark, whose remains were fossilized in its gut contents. 

In the new study, researchers examined three shark fossils found at Calvert Cliffs on the Maryland coast between 2002 and 2016, and a fourth discovered in a phosphate mine in North Carolina in the 1980s. All of the fossils date to the Neogene period (23.03 million to 2.58 million years ago), a time when megalodon (Otodus megalodon), the world’s largest shark on record, stalked the seas. (However, megalodon wasn’t involved in these four attacks.) 

Different views of a vertebra from an ancient requiem shark found in Maryland. Notice the two shark teeth embedded in the fossil. Scale bars equal 1 centimeter.  (Image credit: Perez, V.J. et al. Acta Palaeontological (2021); CC BY 4.0)

Unlike sturdy bone, shark cartilage is a soft tissue made of tiny hexagonal prisms, which rapidly break apart after the animal dies, Perez said. “So, to find cartilaginous elements of a shark’s skeleton is already rare, but to find these skeletal elements with bite traces is truly remarkable,” he said. “There needs to be exceptional circumstances for this predatory interaction to preserve for millions of years and to be recovered by someone who recognizes its significance.”

So, how did these four fossils survive? All are centra, or the vertebrae that make up the spinal column. “The centra are composed of a denser calcified cartilage that preserves better than other parts of the skeleton,” Perez noted. In fact, these four fossils are the first documented ancient shark centra with shark bite marks on them, the research team said.

It’s unclear whether these bites — known as trace fossils, which are fossilized remnants from animals that are not parts of their bodies, like footprints, bite marks or even poop — were made during an active attack or a scavenging event, Perez said. At least one, however, may have come from an attack; one fossil from Maryland that still had two, nearly 1.5-inch-long (4 centimeters) teeth sticking out of it shows signs of healing, indicating that the shark survived the encounter.

A bone analysis revealed the victims were chondrichthyans, a class with 282 species alive today, including  bull sharks, tiger sharks and hammerhead sharks. “We cannot identify the exact species involved in these encounters, but we can narrow it down to some likely culprits,” Perez said.

Based on its shape, the fossil with two embedded shark teeth belongs to the family Carcharhinidae, in one of two genera: Carcharhinus or Negaprion, the researchers said. The embedded teeth may also be from a Carcharhinus or Negaprion shark, the researchers found.

Another Maryland specimen, which also appears to be from the family Carcharhinidae, had bite marks from several attackers — possibly chondrichthyan sharks, lamnid sharks or bony fish. The third Maryland specimen might belong to the Galeocerdo genus, whose only surviving species is the tiger shark (G. cuvier).

The embedded teeth and a gouge mark on the specimens, “suggest that these centra were all bitten very forcefully,” the researchers wrote in the study.

Two of the specimens are now on display at the Calvert Marine Museum in the new exhibit “Sharks! Sink your teeth in!” The study was published online Dec. 7, 2021, in the journal Acta Palaeontologica Polonica.

Originally published on Live Science.

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Noblewoman’s tomb reveals new secrets of ancient Rome’s highly durable concrete

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Enlarge / The Tomb of Caecilia Metella is a mausoleum located just outside Rome at the three mile marker of the Via Appia.

Among the many popular tourist sites in Rome is an impressive 2000-year-old mausoleum along the Via Appia known as the Tomb of Caecilia Metella, a noblewoman who lived in the first century CE. Lord Byron was among those who marveled at the structure, even referencing it in his epic poem Childe Harold’s Pilgrimage  (1812-1818). Now scientists have analyzed samples of the ancient concrete used to build the tomb, describing their findings in a paper published in October in the Journal of the American Ceramic Society.

“The construction of this very innovative and robust monument and landmark on the Via Appia Antica indicates that [Caecilia Metella] was held in high respect,” said co-author Marie Jackson, a geophysicist at the University of Utah.  “And the concrete fabric 2,050 years later reflects a strong and resilient presence.”

Like today’s Portland cement (a basic ingredient of modern concrete), ancient Roman concrete was basically a mix of a semi-liquid mortar and aggregate. Portland cement is typically made by heating limestone and clay (as well as sandstone, ash, chalk, and iron) in a kiln. The resulting clinker is then ground into a fine powder, with just a touch of added gypsum—the better to achieve a smooth, flat surface. But the aggregate used to make Roman concrete was made up fist-size pieces of stone or bricks

In his treatise de Architectura (circa 30 CE), the Roman architect and engineer Vitruvius wrote about how to build concrete walls for funerary structures that could endure for a long time without falling into ruins. He recommended the walls be at least two feet thick, made of either “squared red stone or of brick or lava laid in courses.”  The brick or volcanic rock aggregate should be bound with mortar comprised of hydrated lime and porous fragments of glass and crystals from volcanic eruptions (known as volcanic tephra).

Enlarge / Portus Cosanus pier, Orbetello, Italy. A 2017 study found that the formation of crystals in the concrete used to build the sea walls helped prevent cracks from forming.

Jackson has been studying the unusual properties of ancient Roman concrete for many years. For instance, she and several colleagues have analyzed the mortar used in the concrete that makes up the Markets of Trajan, built between 100 and 110 CE (likely the world’s oldest shopping mall). They were particularly interested in the “glue” used in the material’s binding phase: a calcium-aluminum-silicate-hydrate (C-A-S-H), augmented with crystals of stratlingite. They found that the stratlingite crystals blocked the formation and spread of microcracks in the mortar, which could have led to larger fractures in the structures.

In 2017, Jackson co-authored a paper analyzing the concrete form the ruins of sea walls along Italy’s Mediterranean coast, which have stood for two millennia despite the harsh marine environment. The constant salt-water waves crashing against the walls would have long ago reduced modern concrete walls to rubble, but the Roman sea walls seem to have actually gotten stronger.

Jackson and her colleagues found that the secret to that longevity was a special recipe, involving a combination of rare crystals and a porous mineral. Specifically, exposure to sea water generated chemical reactions inside the concrete, causing aluminum tobermorite crystals to form out of phillipsite, a common mineral found in volcanic ash. The crystals bound to the rocks, once again preventing the formation and propagation of cracks that would have otherwise weakened the structures.

So naturally Jackson was intrigued by the Tomb of Caecilia Metella, widely considered to be one of the best-preserved monuments on the Appian Way. Jackson visited the tomb back in June 2006, when she took small samples of the mortar for analysis. Despite the day of her visit being quite warm, she recalled that once inside the sepulchral corridor, the air was very cool and moist. “The atmosphere was very tranquil, except for the fluttering of pigeons in the open center of the circular structure,” Jackson said.

Enlarge / A plaque on the tomb reads “To Caecilia Metella, daughter of Quintus Creticus, [and wife] of Crassus”.

Carole Raddato/CC BY-SA 2.0

Almost nothing is known about Caecilia Metella, the noblewoman whose remains were once interred in the tomb, other than that she was the daughter of a Roman consul, Quintus Caecilius Metellus Creticus. She married Marcus Licinius Crassus, whose father (of the same name) was part of the First Triumvirate, along with Julius Caesar and Pompey the Great. It was likely her son—also named Marcus Licinius Crassus, because why make it easy for historians to keep track of the family genealogy?—who ordered the construction of the mausoleum, likely built sometimes between 30 and 10 BCE.

A marble sarcophagus housed in Palazzo Farnese is supposedly from the Tomb of Caecilia Metella, but it was probably not the noblewoman’s since it dates to between 180 and 190 CE.  Besides, cremation was a more common burial custom at the time of the lady’s demise, and thus historians believe that the tomb’s cella probably once held a funerary urn, rather than some kind of sarcophagus.

It’s the structure of the the tomb itself that is of most interest to scientists like Jackson and her colleagues. The mausoleum is perched atop a hill. There is a cylindrical rotunda atop a square podium, with an attached castle to the rear that was built sometime in the 14th century. The exterior bears a plaque with the inscription, “To Caecilia Metella, daughter of Quintus Creticus [and wife] of Crassus.”

Enlarge / Lava overlying volcanic tephra in the substructure of the tomb.

Marie Jackson

The foundation is built partly on tuff rock (volcanic ash that has been compacted under pressure) and lava rock from an ancient flow that once covered the area some 260,000 years ago. The podium and rotunda are both comprised of several layers of thick concrete, surrounded by travertine blocks as a frame while the concrete layers formed and hardened. The tower walls are 24 feet thick. Originally there would have been a conical earthen mound on top, but it was later replaced with medieval battlements.

To take a closer look at the tomb mortar’s microstructure, Jackson teamed up with MIT colleagues Linda Seymour and Admir Masic, as well as Lawrence Berkeley Lab’s Nobumichi Tamura. Tamura analyzed the samples at the Advanced Light Source, which helped them identify both the many different minerals contained in the samples and their orientation. The ALS beam line produces powerful x-ray beams about the size of a micron, which can penetrate through the entire thickness of the samples, per Tamura. The team also imaged the samples with scanning electron microscopy.

They discovered that the tomb’s mortar was similar to that used in the walls of the Markets of Trajan: volcanic tephra from the Pozzolane Rosse pyroclastic flow, binding together large chunks of brick and lava aggregate. However, the tephra used in the tomb’s mortar contained much more potassium-rich leucite. Over the centuries, rainwater and groundwater seeped through the tomb’s walls, which dissolved the leucite and released the potassium. This would be a disaster in modern concrete, producing micro-cracking and serious deterioration of the structure.

That obviously didn’t happen with the tomb. But why? Jackson et al. determined that the potassium in the mortar dissolved in turn and effectively reconfigured the C-A-S-H binding phase. Some parts remained intact even after over 2000 years, while other areas looked more wispy and showed some signs of splitting. In fact, the structure somewhat resembled that of nanocrystals.

Enlarge / Scanning electron microscope image of the tomb mortar.

Marie Jackson

“It turns out that the interfacial zones in the ancient Roman concrete of the tomb of Caecilia Metella are constantly evolving through long-term remodeling,” said Masic. “These remodeling processes reinforce interfacial zones and potentially contribute to improved mechanical performance and resistance to failure of the ancient material.”

The more scientists learn about the precise combination of minerals and compounds used in Roman concrete, the closer we get to being able to reproduce those qualities in today’s concrete—such as finding an appropriate substitute (like coal fly ash) for the extremely rare volcanic rock the Romans used. This could reduce the energy emission of producing concrete by as much as 85 percent, and improve significantly on the lifespan of modern concrete structures.

“Focusing on designing modern concretes with constantly reinforcing interfacial zones might provide us with yet another strategy to improve the durability of modern construction materials,” said Masic. “Doing this through the integration of time-proven ‘Roman wisdom’ provides a sustainable strategy that could improve the longevity of our modern solutions by orders of magnitude.”

DOI: Journal of the American Ceramic Society, 2021. 10.1111/jace.18133  (About DOIs).

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NASA’s Webb Space Telescope to Seek Habitable Worlds, Ancient Galaxies

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NASA is about to open a never-before-seen window into the cosmos. Starting next year, astronomers should be able to peer into the atmospheres of planets orbiting distant stars, analyze the aftermath of the universe’s most violent collisions, and look further back in time than ever before.

That’s because the James Webb Space Telescope — JWST, or simply “Webb,” for short — is folded up, full of fuel, and waiting to be loaded onto a rocket in French Guiana.

NASA’s last game-changing space observatory, the Hubble Space Telescope, launched in 1990. It, too, was on a mission to document the 13.8-billion-year history of the universe.

Hubble is still observing the cosmos, and NASA hopes to keep using it for a few more years, possibly into the 2030s. But Hubble could only see so far, and Webb is designed to see even farther.

In collaboration with the European Space Agency (ESA) and the Canadian Space Agency, NASA has spent decades and more than $10 billion building Webb, which is set to launch into space on December 22. While Webb was first conceived of in the 1990s and originally slated to cost $500 million, a redesign and delays both drove up its price tag and pushed back its launch date.

After launch, if all goes according to plan, Webb will spend six months unfolding and adjusting itself, falling into an orbit 1 million miles from Earth. Then it can begin rewriting cosmic history.

The James Webb Space Telescope is unpacked and lifted vertically in a cleanroom at Guiana Space Center in French Guiana, on October 15, 2021

NASA/Chris Gunn



The telescope’s main project is to investigate how galaxies formed and grew after the Big Bang — peering into the universe’s depths to capture images of the first galaxies ever formed. Its infrared cameras are so powerful and precise that they could spot a bumblebee 240,000 miles away — the distance between Earth and the moon.

Webb will also help astronomers investigate mysteries they hadn’t considered when NASA first designed the telescope.

“Webb has this broad power to reveal the unexpected. We can plan what we think we’re going to see, but at the end of the day, we know that nature will surprise us more often than not,” Klaus Pontoppidan, a Webb scientist at the Space Telescope Science Institute, said in a press briefing on November 18.

NASA expects the telescope to probe the secrets of the cosmos for at least a decade. Even the telescope’s first year in space is jam-packed, with nearly 400 investigations from thousands of scientists all over the world, Pontoppidan said.

From peering at Mars to investigating ancient galaxies, here are a few of the most exciting projects that Webb — the most powerful space telescope ever built — is expected to tackle in its first year: 

Light from the first galaxies is still traveling to Earth, and Webb may spot it



The Hubble Ultra Deep Field is the deepest visible-light image of the cosmos. It includes nearly 10,000 galaxies.

NASA, ESA, and S. Beckwith (STScI) and the HUDF Team



As a telescope peers into the distance, it’s also looking back in time. That’s because it takes time for light to travel. When you look at the sun — please, don’t! — you’re seeing light that our star emitted eight minutes ago. When Hubble looks at distant galaxies, it’s seeing light from billions of years ago, as far back as 400 million years after the Big Bang.

“We have this 13.8-billion-year story — the universe — and we’re missing sort of a few key paragraphs in the very first chapter of the story,” Amber Straughn, a scientist on NASA’s Webb team, said in the November 18 briefing. “JWST was designed to help us find those first galaxies.”

Webb is expected to spot galaxies that formed when the universe was just 100 million years old.

It’s 100 times more powerful than Hubble. It’s also using infrared light, which has wavelengths that can cut through dust clouds that may have obscured Hubble’s view, which relied on visible light.

Webb should see deeper into the cosmos and detect galaxies — the first ones formed after the Big Bang — that are too distant and faint for Hubble to pick up.

Looking for gold forged by the universe’s most violent collisions



A supercomputer simulation of a pair of neutron stars colliding, merging, and forming a black hole.

NASA Goddard



For the last six years, gravitational-wave detectors on Earth have been sensing ripples in space-time created by the most violent events in the cosmos: black holes and neutron stars crashing into one another.

Scientists think these collisions forged most of the universe’s heavy elements, like silver, gold, and platinum. Webb will try to confirm that by focusing on distant collisions of neutron stars — the dense cores of stars that have collapsed, ejected their outer layers, and died.

Webb will be able to analyze the entire spectrum of infrared light from those collisions. That will allow astronomers to indentify individual elements like gold or platinum in the explosion debris, based on their wavelengths of light.

This method, called spectroscopy, will help astronomers learn about other objects Webb studies, too.

“Spectra will be the bulk of the science,” Antonella Nota, a Webb scientist who leads the ESA office at the Space Telescope Science Institute, said in the briefing. “While an image, we say is worth 1,000 words, spectra for astronomers are just worth 1,000 images.”

Our first glimpse at the atmospheres of planets that could host life



An artist’s impression of the super-Earth exoplanet K2-18b.

ESA/Hubble, M. Kornmesser



When it’s not busy studying the most massive objects and ancient galaxies in the universe, Webb will search for less extreme environments, worlds where conditions could be just right to give rise to life.

Exoplanets — worlds orbiting other stars — were barely a field of study when NASA began designing Webb. Two decades later, astronomers have identified dozens of exoplanets that could be temperate enough for alien life. They’re not too cold, not too hot, just right for water — but only if they have hospitable atmospheres.

Webb will watch potentially habitable exoplanets pass in front of their stars, and analyze the spectra of starlight that shines through the planets’ atmospheres. That spectroscopy will indicate to scientists whether the air on other worlds contains compounds that could point to life, like carbon dioxide, methane, or water.

“This telescope is definitely our next big step in our search for potentially habitable planets,” Straughn said.



The James Webb Space Telescope in a Northrop Grumman cleanroom in Redondo Beach, California, on March 4, 2020.

NASA/Chris Gunn



These aren’t necessarily Earth-like planets. Stars like the sun are so big and bright that Webb wouldn’t be able to see the tiny Earth-like planets orbiting them. That’s a job for the next great space telescope. Instead, Webb will look at rock planets orbiting stars that are much smaller and dimmer.

Some of its first targets will be planets circling a small star, TRAPPIST-1, just 39 light-years away.

The star has seven rocky planets, three of them in its “Goldilocks zone,” meaning they’re just the right distance to have temperatures that would allow liquid water to exist on their surfaces.



An artistic rendering of what it might look like on the surface of the planet TRAPPIST-1f.

NASA/JPL-Caltech


Webb is also set to zoom in on uninhabitable, but fascinatingly extreme, planets. At least one of the planets on its roster is so close to its star that its surface is molten, and it may even rain lava there. Webb should be able to detect that lava rain.

The telescope will also examine every object in our solar system, starting with Mars and working its way outward to the icy objects beyond Pluto.

In those planets, stars, and galaxies, near and far, Webb is sure to uncover major surprises. 

“Webb will probably also reveal new questions for future generations of scientists to answer — some of whom may not even be born yet,” Pontoppidan said.

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Ancient DNA Discovery Reveals Woolly Mammoths, Wild Horses Survived Thousands of Years Longer Than Believed

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Researchers used DNA capture-enrichment technology developed at McMaster to isolate and rebuild the fluctuating animal and plant communities during the Pleistocene-Holocene transition. Credit: Julius Csotonyi

Mere spoonsful of soil pulled from Canada’s permafrost are opening vast windows into ancient life in the Yukon, revealing rich new information and rewriting previous beliefs about the extinction dynamics, dates, and survival of megafauna like mammoths, horses, and other long-lost life forms.

In a new paper, published in the journal Nature Communications, researchers from McMaster University, the University of Alberta, the American Museum of Natural History, and the Yukon government present a 30,000-year

Cored permafrost sediments are extracted from the Klondike region of central Yukon. Credit: Tyler Murchie

They reconstructed the ancient ecosystems using tiny soil samples which contain billions of microscopic genomic sequences from animal and plant species.

The analysis reveals that mammoths and horses were already in steep decline prior to the climatic instability, but they did not immediately disappear due to human overhunting as previously thought. In fact, the DNA evidence shows that both the woolly mammoth and North American horse persisted until as recently as 5,000 years ago, bringing them into the mid-Holocene, the interval beginning roughly 11,000 years ago that we live in today.

Through the early Holocene the Yukon environment continued to experience massive change. Formerly rich grasslands—the “Mammoth Steppe”—were overrun with shrubs and mosses, species no longer held in check by large grazing herds of mammoths, horses, and bison. Today, grasslands do not prosper in northern North America, in part because there are no megafaunal “ecological engineers” to manage them.

Tyler Murchie is a postdoctoral researcher in McMaster’s Department of Anthropology and a lead author of the study. Credit: Georgia Kirkos

“The rich data provides a unique window into the population dynamics of megafuana and nuances the discussion around their extinction through more subtle reconstructions of past ecosystems,” says evolutionary geneticist Hendrik Poinar, a lead author on the paper and director of the McMaster Ancient DNA Centre.

This work builds on previous research by McMaster scientists who had determined woolly mammoths and the North American horse were likely present in the Yukon approximately 9,700 years ago. Better techniques and further investigation have since refined the earlier analysis and pushed forward the date even closer to contemporary time.

Hendrik Poinar is an evolutionary geneticist, a lead author on the paper and director of the McMaster Ancient DNA Center. Credit: Georgia Kirkos

“Now that we have these technologies, we realize how much life-history information is stored in permafrost,” explains Tyler Murchie, a postdoctoral researcher in McMaster’s Department of Anthropology and a lead author of the study.

“The amount of genetic data in permafrost is quite enormous and really allows for a scale of ecosystem and evolutionary reconstruction that is unparalleled with other methods to date,” he says.

“Although mammoths are gone forever, horses are not,” says Ross MacPhee of the American Museum of Natural History, another co-author. “The horse that lived in the Yukon 5,000 years ago is directly related to the horse species we have today, Equus caballus. Biologically, this makes the horse a native North American mammal, and it should be treated as such.”

Scientists also stress the need to gather and archive more permafrost samples, which are at risk of being lost forever as the Arctic warms.

Reference: “Collapse of the mammoth-steppe in central Yukon as revealed by ancient environmental DNA” by Tyler J. Murchie, Alistair J. Monteath, Matthew E. Mahony, George S. Long, Scott Cocker, Tara Sadoway, Emil Karpinski, Grant Zazula, Ross D. E. MacPhee, Duane Froese and Hendrik N. Poinar, 8 December 2021, Nature Communications.
DOI: 10.1038/s41467-021-27439-6



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