Along the Apennines, this process created a push-and-pull of forces. As the African plate subducted under the Eurasian plate, the boundary of the subduction zone was making its own march toward the African plate, causing the crust on the Eurasian side to stretch and thin, creating two large basins: an older one in the Mediterranean Sea west of Corsica and Sardinia, and a younger one, the Tyrrhenian Sea segment of the Mediterranean east of Corsica and Sardinia, which formed roughly 10 million years ago. Until now, the driver behind the extension creating these basins and the compressional forces building the Apennines has not been entirely clear, Tavani said.

To better understand this unusual tectonic movement, Tavani and his colleagues integrated earthquake record and ground movements from GPS and satellite measurements with the tectonic models of the plate movements and found that under the Apennines, the lower crust is peeling away and dropping into the mantle — a process called delamination. It is this delamination, and not the subduction of one plate under another, that causes most of the seismic activity in the Appennines, the researchers reported in their study published this month in the journal Communications Earth & Environment. In a few more million years, Tavani said, the lower crust will finish dropping away and the two plates will weld together.

There are other places around the world where similar processes are happening, such as in the Hellenic trench south of Greece, Tavani said. The findings "could be applied to other several systems," he said, "because in the end, it is a kind of very late-stage plate tectonics."

'> Earth's crust is 'unzipping' beneath Italy — and that could explain most of the earthquakes in the region Curiosity rover has officially seen the sun rise and set over Mars' reddish horizon more than 5,000 times in its quest to discover if life ever existed there. The rover was originally planned to operate for only two years, but the mission is still going strong more than 14 years after landing on Mars in August 2012.

During that time, the rover has weathered global dust storms and climbed more than 3,200 feet (1,000 meters) up a mountain — although its tires have gotten some rather large holes in them in the process. The rover still uses its 17 cameras to take hundreds of photos every single sol (Martian day), beaming a total of more than 780,000 photos back to Earth for scientists to analyze while mission controllers decide where the rover should roam next.

In honor of the intrepid rover's 5,000th day on the Red Planet, here are 10 of the most iconic photos Curiosity has snapped for Earthlings to admire.

Sol 548: Mount Sharp on the horizon

Curiosity snapped this photo of Mount Sharp on Feb. 19, 2014, about a year and a half after it landed on Mars. At the time, scientists were hopeful the rover could make it to the base of the 3.4-mile-high (5.5 kilometers high) mountain to explore interesting terrain previously seen from space. As the years passed, Curiosity more than surpassed that goal; the rover has climbed more than half a mile up into the mountain's foothills, traveling a total of more than 23.6 miles (38 km) from its landing spot, all while conducting important science along the way.

Sol 956: Blue skies on Mars

Curiosity took a photo of the Martian sunset in color for the first time on April 15, 2015, revealing a brilliant blue sky just before the sun dipped behind the shrouded mountains in the distance. The Martian sky is usually yellow to orange, according to NASA. Fine dust particles in the atmosphere scatter red and yellow light across the entire sky. However, the dust is just the right size for some blue light to slip past, so most of the light in the sky near the sun is blue. The effect is much more pronounced when the sun is low in the horizon.

Sol 1128: Curiosity Selfie at Namib Dune

Curiosity has taken numerous selfies over the course of its mission, although the process is a bit more involved than holding up a camera and smiling. This selfie was made from 57 separate images taken on Jan. 19, 2016 using a camera attached to its robotic arm. Here, Curiosity is standing next to Namib Dune, one of the many dark sand dunes that make up the Bagnold Dune Field near Mount Sharp. Curiosity sampled the sand for analysis and scuffed the dune with its wheels so scientists could see how the sand moved.

Sol 1819: Curiosity leaves a thumbprint in the dust

Mars is extremely dusty. The reddish dust gets swept into the atmosphere and cast across most of the planet's surface, making it difficult for scientists to figure out what materials are on the surface just by looking at them. On Sept. 17, 2017, Curiosity dusted off the surface of a rock at Vera Rubin Ridge and took a picture for geologists to compare to rocks on Earth. Based on the reddish purple color, geologists think this rock is fine-grained hematite split by fractures filled with calcium sulfate minerals. It hints that Mars might be a lot more colorful underneath its dusty blanket. Scientists have since discovered ruby-like materials embedded in Martian rocks.

Sol 3466: Totally not a door for aliens

On May 7, 2022, Curiosity sent a curious photo back to Earth that appears to show a small door carved into the face of a cliff. It's hard not to imagine little green people entering it after taking their little green dogs for a stroll across the dusty landscape, but it's not actually a doorway for Martians. The 3-foot-tall opening's boxy shape is caused by vertical fractures intersecting with horizontal layers in the rock, according to NASA. The cliff is highly fractured, and a large chunk of rock that likely fell from the "doorway" is clearly visible nearby.

Sol 3724: Iridescent feather in the sky

Just after the sun went down on Jan. 27, 2023, Curiosity took this photo of a noctilucent (night-shining) cloud that formed much higher in the Martian atmosphere than most other clouds do. Any clouds on Mars are rare, but this one is extra special. Since this cloud is so high up, it's much colder — making scientists think it's made of carbon dioxide (dry ice) instead of water ice. The iridescent colors in the cloud indicate the ice particles making up the cloud are all around the same size, which means the cloud likely just formed at the time of the photo.

Sol 3725: Curiosity finds "Cacao"

The very next day after cloud-gazing, on Jan. 28, 2023, Curiosity found an iron-nickel meteorite measuring about a foot across. The meteorite, nicknamed "Cacao," is one of a handful of meteorites Curiosity has photographed. The rover zapped part of the meteorite with a laser and measured the vapor released to identify what materials the rock was made of. Since Mars is cold and dry compared to Earth, meteorites last much longer on its surface than they do here, and they give clues about how the Martian atmosphere has changed over time. Large iron meteorites discovered on Mars indicate the planet once had a denser atmosphere than it does today.

Sol 4208: Elemental sulfur crystal surprise

In June 2024, Curiosity unintentionally ran over a rock and crushed it, revealing a yellow, odorless surprise: rare crystals of elemental sulfur. While Mars has plenty of minerals that contain sulfur, like sulfate, this was the first time pure sulfur was found. The crystal fragments are about 5 inches (12.7 centimeters) across. On Earth, pure sulfur is formed from volcanic and hydrothermal activity, along with other geologic processes. It's not clear yet how these crystals formed on Mars.

Sol 182 - 4263: All 42 drill samples

Curiosity has collected and analyzed 42 rock samples so far using a small drill attached to a robotic arm. The drill powders the rock so that the samples can be transported to Curiosity's science instruments, which measure their chemical composition. Each sample site is carefully chosen because the rover can only do a limited number of samples before it runs out of special sample cups. This mosaic image shows the impressive variety of materials that Curiosity has sunk its drill into.

Sol 4671: Exploring Martian spiderwebs

Researchers have been intrigued by large geologic structures like stone "spiderwebs" on the Martian surface, previously seen by spacecraft orbiting the planet. Curiosity visited them on the ground, taking this picture of the low ridges and hollows, called boxwork, on Sept. 26, 2025. The ridges, made from hardened minerals deposited by water seeping into cracked rock, are what's left after billions of years of erosion wore away the softer rock around them.

Curiosity's journey continues today. After leaving the boxwork structures last March, the rover set off to explore more of the Martian landscape with its cameras as busy as ever, looking for more evidence that Mars once had the water and chemistry to possibly support ancient microbial life.

What do you know about the Red Planet? Test your knowledge with our Mars quiz!

'> Curiosity's top 10 photos of Mars after 5,000 days of exploration Dr. Meghana Tanwar, a medical consultant at the Aravind Eye Hospital in India who co-authored a report of the case. The texture and color of the projections suggested they might be teeth, she told Live Science in an email.

Initially, the doctors thought the points also might have been related to a teratoma, a rare type of tumor that can include different types of tissue, including bone and tooth tissue. They also wondered if the projections might be a foreign body in the eyelid. They conducted a CT scan to take a closer look.

The diagnosis: The scan revealed that the projections were indeed part of a tooth.

"The structure of a lone tooth in the superior orbit was quite obvious," Tanwar said. "Superior orbit" refers to the upper eye socket, and the tooth had poked out in the small space between the boy's eyelid and eyebrow.

Teeth that develop and erupt in abnormal locations are known as ectopic teeth. This umbrella term includes teeth that are in the mouth but erupt outside their typical positions; for instance, in about 2% to 6% of people, their first permanent molars grow "out of place" in the expected line-up of teeth.

In this case, though, the patient had an ectopic tooth that appeared completely outside the dental arch, which is far rarer.

The treatment: The doctors surgically removed the ectopic tooth from the patient's eyelid and found that it was a mature canine tooth. It didn't have any features that suggested it was part of a teratoma.

"Since the imaging done did not show the presence of any other ectopic teeth, the likelihood of him having another one are unlikely," Tanwar noted.

What makes the case unique: This is not the first ectopic tooth in the medical literature, but it was in a very notable location.

"To the best of our knowledge this is the first and only ectopic tooth reported in the superior orbit," Tanwar said. Previously, they've been reported in the nasal cavity and the bottom of the orbit, under the eye, she noted. According to MedPage Today, they've also been found in the nostrils, chin and maxillary sinus, which is located inside the cheekbone.

"This was a first not just for us but the world over," Tanwar said of the case. "We were very surprised by it."

Prior to the case, Tanwar had personally seen a tooth in the bottom of the eye socket of a different patient, but it was part of a rare type of mass called an odontogenic choristoma.

In this teen's case, the underlying cause of the ectopic tooth was unknown. Hypotheses suggest that, in general, ectopic teeth may grow out of place due to developmental disorders, physical trauma, infection or genetic factors.

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

This article is for informational purposes only and is not meant to offer medical advice.

'> Weird spikes poking through a teen's eyelid turned out to be a wayward tooth

Despite having discovered thousands of exoplanets, we have not detected convincing evidence of alien life on any of them. But astronomy is reaching a point where powerful telescopes can zoom in on many more potentially habitable worlds. Planets that orbit M dwarfs, which are small stars cooler than the sun, are particularly promising targets because they have a unique observation window. When a planet passes in front of one of these stars, it blocks a relatively large fraction of the star's light, making the planet and its atmosphere easier to detect.

There are also a lot of them. M dwarfs are the most common type of star in the Milky Way. However, if we misunderstand how these stars interact with planetary atmospheres, we may misinterpret the significance of observations from some of the most promising planets.

The most-studied biosignatures are methane, oxygen and ozone. On Earth, these are often produced by biological processes, with ozone acting as an indirect indicator of oxygen. But even on our home planet, molecules typically associated with life are not unambiguous biological fingerprints. These molecules can be produced by geological and chemical processes, as well as via atmospheric reactions with light from the sun.

A potential biosignature detection found elsewhere in the cosmos is therefore a clue, not proof of life. We can't interpret the chemical signals coming from a potentially habitable planet without understanding the star that illuminates it. M dwarfs produce ultraviolet radiation that can break apart molecules and trigger chemical reactions in the atmosphere of an orbiting planet. The intensity and wavelength of the radiation influence which molecules form and survive, as well as how abundant they become. Two planets with otherwise identical properties could develop very different atmospheres simply because they orbit stars with different ultraviolet emissions. Radiation from a star could therefore make the same level of biological activity appear stronger on one planet than on another, or make nonbiological chemistry look like life. A recent study submitted to the preprint server arXiv Aug. 19 demonstrated this using entirely simulated planets. The researchers, led by University of California, Santa Cruz astronomy graduate student C. Evan Davis, simulated Earth-like planets orbiting two different types of M dwarf with ages ranging from 650 million to 5 billion years.

The team considered atmospheres resembling that of Earth during the oxygen-rich preindustrial era and the Archean eon (about 4 billion to 2.5 billion years ago), during which the first life-forms emerged but atmospheric oxygen was scarce. The models considered the stars' usual, or "quiescent," ultraviolet emission rather than short-lived flares. By changing the modeled stars' ages and ultraviolet radiation while keeping the planets comparable, they investigated how a star's evolution changed an atmosphere and the signals astronomers might observe.

One of the clearest differences the team found appeared in methane. Simulated planets with preindustrial atmospheres orbiting 5 billion-year-old M dwarfs accumulated up to 10 times more methane than equivalent planets simulated to orbit the younger 650 million-year-old stars. The methane signals produced in the simulated data were up to 68% stronger for the older systems. The weaker UV emission from the older M dwarf allowed methane to survive longer and accumulate in the simulated planetary atmospheres. The stronger methane signal could make a planet orbiting an older star appear to support more biological activity, when this difference was actually caused by the UV emission of the host star.

An even more striking result came from ozone. For the simulated Archean Earth-like planets, which were low in oxygen and rich in carbon dioxide (CO₂), the stronger UV radiation from younger M dwarfs broke apart more CO₂. This kick-started reactions that created oxygen and ozone without any life involved. Some model planetary atmospheres contained more than 100,000 times as much ozone as equivalent models around older stars. A hypothetical observer could misinterpret the resulting ozone signal as indirect evidence of biologically produced oxygen. Ozone is not useless as a biosignature, but these simulations show that it cannot be interpreted confidently without knowing the UV environment that shaped the atmosphere.

Of course, astronomers are already aware that a single molecule would not prove the existence of life on an exoplanet. Researchers use atmospheric models, look for combinations of gases, and consider nonbiological explanations before describing a signal as a potential biosignature. These methods remain valuable for identifying the most promising planets for further investigation, even when our knowledge of their stars is incomplete. Some might argue that these methods provide a sufficiently reliable first assessment and we should reserve more detailed stellar observations for the strongest candidates.

But even the best atmospheric model can mislead us if the stellar radiation isn't accounted for correctly. Ultraviolet observations of M dwarfs remain limited, so researchers often rely on estimates from similar stars. However, two M dwarfs that might appear similar can produce very different levels of UV radiation. Atmospheric models based on currently available stellar measurements may be sufficient for selecting promising targets but not for deciding whether the origin of a signal is biological. Simply acknowledging that the star matters isn't enough; we need accurate information about the specific star hosting the planet.

So before we train our telescopes on promising exoplanets, we need to study their host stars. This requires repeated UV observations, typically with different telescopes or instruments or at different time periods than you'd use to study the exoplanet. These observations can characterize how the host star's emission varies over time, while better stellar-age estimates — which can be calculated from properties such as rotation and magnetic activity— will reveal how that radiation has evolved.

Then, once we do start studying an exoplanet, potential biosignatures must be analyzed and interpreted using models informed by accurate measurements of the host star. As recommended in the preprint study, astronomers should also search for accompanying molecules, such as carbon monoxide, that could reveal whether ozone arose through reactions between light and carbon dioxide rather than from biology. The first convincing discovery of life on another planet will depend on an understanding of not only that planet but also the star that shaped the atmosphere we observe.

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'> The hunt for extraterrestrial life is fundamentally flawed. But there's a fix.

Archaeologists think the hoard was buried at the time of the Emperor Hadrian, who ruled from A.D. 117 to 138, because the most recent coin was minted in 124 or 125.

But the coins span more than three centuries: the oldest was minted in 148 B.C., during the time of the Roman Republic; while most of them are from the time of the Flavian emperors — Vespasian and his sons, Titus and Domitian — from A.D. 69 to 96.

Silver signal

The statement praised the metal detectorist, Oliver Riedl, who found the hoard and stopped digging after unearthing 15 of the coins. At that point, his metal detector signaled that something much larger was hiding underground.

"It was clear to me that there was something bigger in the ground here," Riedl said in the statement. "I therefore immediately informed the office."

Riedl is licensed by the state to use his metal detector and has been trained by regional archaeological authorities, the statement said. (Illegal metal detectorists also operate in Germany, but are known to often disrupt the archaeological value of their finds).

Archaeologists from the Rhineland regional government soon investigated the find and excavated the entire hoard of 934 Roman silver coins. The block of earth that contained the coin hoard was removed whole and X-rayed before it was opened, the statement noted.

Erich Claßen, the head of archaeology for the Rhineland regional government, said it seemed that the original owner collected most of the coins in about A.D. 100, but didn't actually bury them until Hadrian's time.

"We can only speculate about the motives, but very likely someone wanted to keep this money safe," he said in the statement. "Banks did not exist at that time."

But whoever buried it never came back. "It is possible that the owner died beforehand without being able to pass on the knowledge of the coins," Claßen said.

Buried treasure

Marjanko Pilekić, a numismatist, or coin expert, at the German Historical Museum in Berlin who wasn't involved in the find, said it was significant that the hoard was unearthed just inside the northern frontier of the Roman Empire demarcated by the Roman limes, which ran along the Rhine nearby.

He told Live Science in an email that the location suggested when the hoard had been purposefully buried: "In this case, we can cautiously assume that the hoard was buried not long after the most recent coin was minted," Pilekić said.

Outside the Roman Empire, however, in the Barbaricum – the "barbarian" regions beyond, according to the Romans — such hoards of coins were often buried much later, he said.

While its historical value is priceless, the worth of such a hoard during the second century A.D. would have been considerable: 300 denarii was the yearly pay of a Roman legionary at the time of Hadrian, of which around half was deducted for food and equipment, regional archaeologist Rahel Otte, who led the excavation, said in the statement.

This means that a legionary "would have had to save all his available money for about six years to accumulate the Wesseling treasure find," she said.

She added that it was unclear who had buried the hoard, but it may have been someone who lived on one of the Roman estates in the area.

From Augustus to Nero, see how much you know about ancient Rome's famous leaders with our Roman emperor quiz!

'> 'There was something bigger in the ground here': Metal detectorist in Germany discovers giant Roman-era hoard from time of emperor Hadrian