For most of the last century, T. rex was pictured as a sluggish, tail-dragging reptile that had to warm up in the sun before it could go anywhere. Then, further research changed that view, replacing it with the active, bird-like animal shown in the movie Jurassic Park. But whether T. rex used warm blood to power that activity remained a question. Now we might have gotten closer to an answer.

A team of researchers led by Randon J. Flores and Robert A. Eagle, geochemists at the University of California, Los Angeles, has measured the T. rex body temperature by analyzing its teeth. This dental thermometer read about 36° Celsius—roughly the body temperature of a modern elephant.

Dental thermometry

Paleontologists have long argued about dinosaur physiology based on indirect evidence like bone microstructure, growth rates, and where fossils turn up on the map. Some studies suggested many dinosaurs were endotherms, generating their own body heat like birds and mammals. Others argued that each lineage may have had its own thermal strategy.

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For decades, astronomers thought rings were something only giant planets had. That changed in 2013, when a small, dark body orbiting between Saturn and Uranus passed in front of a star and blinked twice on either side of the main event, revealing two narrow rings around an object barely 250 kilometers across. “It was a surprise,” says Pablo Santos-Sanz, an astronomer at the Instituto de Astrofísica de Andalucía in Granada, Spain. Ever since, the question has been what such rings are made of and how long they can last.

In a recent study, Santos-Sanz and his colleagues used the James Webb Space Telescope to watch the same body, now known as Chariklo, pass in front of a background star again. They found one of its rings had grown denser and the other had almost vanished. We don’t know exactly why.

Shadowing a star

The technique behind the observation is simple. “We predict when a Solar System object passes in front of a star,” Santos-Sanz said. The starlight dims for a moment, and the shape of that dip reveals the size, shape, and surroundings of the object that caused it. “This is particularly challenging for minor bodies, and more challenging for distant minor bodies,” he said.

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For a long time, sleep research has treated the cerebral cortex as a passive follower reacting to signals from the deep brain. “Usually, sleep is associated with being controlled by subcortical regions,” said Geoffrey Terral, a neuroscientist at the Albert Einstein College of Medicine in New York.

The cortex is where the slow rhythms of deep sleep can be seen, but researchers assumed the signals that triggered them originated elsewhere. In a recent Nature study, Terral and Renata Batista-Brito, who runs the lab, report a population of cortical cells that challenges that assumption.

These cortical cells make up only around one percent of the cortex's inhibitory neurons, and switching them on in a mouse puts the animal to sleep. “What our work shows is that the cortex can not only see this rhythm but also initiate it by itself, and this is sufficient to promote sleep,” Terral said.

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Almost a hundred years ago, physicists theorized out what free fall should do to a quantum wave. If the solution they came up with is wrong, quantum mechanics and Einstein's theory of gravity flatly contradict each other. But testing it has been impossible because nobody has managed to build an interferometer that could perform the necessary measurement.

Now, a team led by Ron Folman, a physicist at Ben-Gurion University of the Negev, with collaborators in Germany, the UK, and the US, including Nobel laureate Roger Penrose, has done it. They built a new interferometer that gives a single atom two possible paths at once: one that involves a free fall, and another where it is held perfectly still. Both paths end at the same place at the same moment, allowing the team to measure what the fall does to a wave-like property of the atom.

Long time coming

Ever since Galileo, physicists have known how to describe a falling object—where it is, how fast it goes, or how quickly it accelerates. Quantum mechanics, though, insists that every object is also a wave. “Every particle, doesn't matter if it's a car or a spaceship or an atom, is a wave,” Folman says. “Everything that is a wave, like sea waves or sound waves, goes up and down. And if you're up or down, this is measured by something called a phase. A phase just tells you if you are at the top of the wave or at the bottom.”

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The standard explanation for why rain causes corrosion is that water carries dissolved salts and acids to a surface, constant drumming of raindrops abrades whatever protective coating is on it, and oxygen does the rest. Nearly all our tools to prevent this—paints, polymer films, or oxide layers—are built around this idea. But we’ve apparently been missing something important about the rain.

A new study led by Zhongyuan Ni, Rüdiger Berger, and Hans-Jürgen Butt at the Max Planck Institute for Polymer Research in Mainz, Germany, has shown that water drops routinely arrive at a surface carrying an electrical charge large enough to punch through an insulating coating. Not scratch it. Not slowly dissolve it. Electrically blow a hole in it, the way a spark jumps a gap.

Charged rain

The starting point of the study is a phenomenon called "slide electrification," which has only been properly quantified in the past few years. When a water drop slides across an insulating surface like a leaf, a painted wall, a windowpane, or a plastic panel, it strips charge from that surface and leaves an opposing charge behind. The voltages involved are not trivial. Drops charged this way have been measured at up to 9,000 volts.

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Every few years, El Niño or its cool counterpart, La Niña, shifts rainfall across the tropics, dries out Australia, floods parts of Peru, and rearranges the weather on most of the planet. The two are the warm and cold swings of a single system, the El Niño–Southern Oscillation, or ENSO, and that system is the largest source of year-to-year climate variation on Earth. Its swings sit atop the steadily rising temperatures driven by global warming.

But we didn't know whether global warming was making it stronger. It’s possible that the added energy in the atmosphere and oceans was causing its swings to be more dramatic.

“We've been seeing some very strong El Niño events in the late 20th and early 21st century, and what we didn't know was how unusual those are,” said Julie Cole, an environmental scientist at the University of Michigan. Because models disagree with one another and the instrumental data are too short to separate a trend, Cole’s team reconstructed a thousand-year-long ocean surface temperature record by analyzing fossilized Galápagos corals.

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Our leading hypothesis for how our memories are stored is that when you learn something, the connections among neurons involved get stronger and physically larger, and that constitutes the memory. The trouble is that these connections significantly change over time—they’re plastic.

“If you compare the arrangement of these connections on day one with the same on day four or five, it's very, very different," says Kazumasa Tanaka, a neuroscientist at the Okinawa Institute of Science and Technology Graduate University in Japan. To learn how a memory that can last for years can sit on hardware that shifts every few days, Tanaka’s team made the shift a bit more dramatic. In a recent Science study, they induced a hibernation-like state in mice, which basically erased the state of more than half of their synapses. And yet the mice apparently have kept their memories.

Hibernation on demand

Hibernation is a specialty of squirrels, hamsters, and bears, but the neural circuit that triggers it is conserved across mammals, and is present in species that never hibernate in the wild—like mice. In June 2020, a team of researchers led by Takeshi Sakurai, a neuroscientist at the University of Tsukuba and a collaborator on Tanaka’s study, developed a technique to artificially activate this hibernation circuit. This can be done by activating a population called Q neurons in a region of the hypothalamus.

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Solar storms, like the one in August 1972 that hit during the gap between the Apollo 16 and Apollo 17 missions, throw bursts of protons intense enough to raise an astronaut's cancer risk or even cause radiation sickness. Earth's atmosphere and magnetic field absorb this radiation, but crews heading to the Moon or Mars won't have that protection, and no spacecraft built so far has enough shielding to stop it.

A team led by Jordan Houri and Oren Milstein of StemRad, an Israeli-American startup developing personal protective equipment against radiation, proposed that we could solve this by shielding the astronauts instead of shielding the spacecraft.

To test this idea, StemRad’s team flew a wearable radiation-shielding vest called AstroRad to the Moon and back aboard NASA's uncrewed Artemis I mission, then used the flight data to calculate how it would perform during an actual solar storm. It turns out the vest would perform roughly as well as the Orion’s heavily shielded onboard shelter the crew was supposed to hide in to wait out a storm.

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Mount Toba was the biggest volcanic eruption in the last 2.6 million years, and some have suggested it nearly wiped out humanity. Around 74,000 years ago, a caldera on what is now Sumatra emptied thousands of cubic kilometers of magma in about two weeks, roughly a thousand times more than Mount Pinatubo spewed out in 1991. “People thought it might have caused massive cooling of the planet, and hence threatened the survival of our ancestors,” says Jinheum Park, a geoscientist at Johannes Gutenberg University in Mainz, Germany.

Park and his colleagues went looking for the records of that catastrophe in the mud taken from the bottom of a small crater lake on the Kenya-Tanzania border. They found instead that the effects of the Mount Toba eruption lasted under two years and amounted to perhaps half a degree of cooling.

Muddy calendars

Volcanic eruptions inject sulfur dioxide into the stratosphere, where it becomes a haze of tiny droplets that reflect sunlight back into space. Bigger eruptions eject more sulfur dioxide and, in principle, cause more cooling. But this trend stops working when the eruption exceeds a certain magnitude. “Bigger sulfate aerosols settle quickly, because they are heavier,” Park explains. This quick settling makes them less effective in scattering incoming solar radiation.

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Wherever two fluids slide past each other at different speeds, the boundary between them buckles, then curls, then rolls up into vortexes. It’s called the Kelvin-Helmholtz instability, and the physics behind it was worked out in the late 1860s. We know this instability explains why wind causes ripples on the surface of water and clouds shear into a row of curves.

For decades scientists argued the same thing must be happening with plasma on the surface of the Sun, and yet nobody had been able to confirm it. Now, a team led by David Kuridze and Friedrich Wöger of the National Solar Observatory reports that Kelvin-Helmholtz instabilities are not just visible on the Sun, but they’re ubiquitous. Their new study proposes that this may change the way we think about how heat, mass, and magnetic energy move through the Sun's atmosphere.

Telescope’s test drive

The reason plasma whirlpools on the Sun stayed hidden for so long is rather trivial: They are very small. Their scale sits below what telescopes with mirrors smaller than 2 meters can resolve. For most of the history of solar physics, that has ruled out every telescope on Earth. This changed when the US National Science Foundation opened the Daniel K. Inouye Solar Telescope, a 4-meter instrument in Hawaii and the largest solar telescope in the world. The telescope entered its operational phase back in November 2021.

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A fruit fly hunting a piece of rotting fruit or a mate navigates by smell, following plumes of odor. Out in the wild, turbulent air swirls these plumes into a chaotic, broken landscape—dense chemical filaments laced through long stretches of clean air. A fly trying to find the source gets the smell in stutters, from constantly shifting directions, with no guarantee that a next whiff is coming at all.

Scientist had little idea of how fruit flies manage this chaotic signal with a brain the size of a pinhead. For a long time, biologists stood by the “surge and cast” model, which posited that insects solved this with hardwired reflexes. The idea was that, when a fly registers the plume with olfactory neurons in its antennae, it simply flies upwind until it’s gone and then flies side to side attempting to catch it again. But now a team led by Vanessa Ruta, a neuroscientist at the Rockefeller University, has shown that fruit flies do something far more advanced.

A treadmill for flies

The trouble with the traditional surge and cast model is that it struggles to explain how an insect tracks a meandering plume across long distances. Chemical cues floating in the air in the natural environment are often sparse and unreliable. But those same features make the mechanism behind olfactory navigation notoriously difficult to test. "Odors are invisible," Ruta says, "and often they're carried along by turbulent airflow." We’ve got no way of knowing what the animal is smelling from one moment to the next.

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Human eyes don’t register the infrared portion of the light spectrum because infrared photons don't carry enough energy to trigger the signaling pathway inside our light-sensing cells. But we’ve been able to make devices that give us a visual representation of what’s happening in the infrared.

A team at the Beijing Institute of Technology, led by Xin Tang and Ge Mu, has now built a device that lets people see infrared in a new way. Instead of just translating it to visible shades of green as it’s done in standard night-vision goggles, it translates different infrared wavelengths into distinct parts of the visual spectrum, giving the eye something closer to natural vision.

Researchers achieved that by combining mercury telluride colloidal quantum dots, which absorb infrared light, and a dual-layer OLED, which converts that absorbed energy into visible color. Stacked together with the right internal wiring, they make incoming infrared radiation come out the other side as an ordinary-looking, full-color image.

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Naked mole rats are weird. They spend their lives almost entirely underground, are largely insensitive to some kinds of pain, can persist without oxygen for a long time, rarely develop cancer, and can live past 30 years, which is decades longer than similarly sized rodents. They are also eusocial, like ants, bees, or termites—in a colony that can hold more than a hundred animals, only one female, the queen, breeds.

We didn’t know how exactly naked mole-rat queens stop other females from breeding. For a long time, our leading hypothesis was bullying and violence, but that may be a bit impractical, given their kingdoms are vast networks of tunnels that can stretch for up to three kilometers. But now a team of Lewin Lab scientists at Max Delbrück Center for Molecular Medicine in Berlin discovered it’s actually just one part of a sophisticated olfactory signaling program.

Running on smell

"It's very clear that mole rats actually have quite big noses and smell a lot," says Gary Lewin, a neurobiologist at the Max Delbrück Center for Molecular Medicine and senior author of the study. Naked mole rats have around 1200 olfactory receptor genes, more than mice (which have roughly 1,000 of them) and way more than the few hundred in humans. They're also blind. "They have to be able to navigate and move around without vision, so smell is one of those things that’s enhanced," Lewin said.

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WD 1856 b is the only confirmed case of a planet that survived the death of a Sun-like star. It’s a Jupiter-size world orbiting a white dwarf—the burned-out remnant of a Sun-like star. Now, a team of astronomers has used the James Webb Space Telescope to take a closer look at this planet for the first time, and what they found makes an already strange system even stranger.

A feeding frenzy

WD 1856 b was an accidental discovery. Astronomers pointed the TESS observatory at a sample of roughly 2,000 white dwarfs in 2020. These stars are the remains of a Sun-like star that have already gone through a red-giant phase, leaving behind an Earth-size body that’s primarily composed of elements like carbon and oxygen. The TESS team was searching for small objects like comets or asteroids that might transit across the face of these dead stars.

What they found in the WD 1856 system was a gas giant. “As soon as they looked at it, they said, okay, that’s weird,” said Christopher O’Connor, a theoretical astrophysicist at Cornell University and co-author of the recent Nature study on WD 1856 b.

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Albert Einstein’s general theory of relativity predicts that a rotating mass like the Earth pulls the fabric of space and time around with it in a perpetual swirl. This phenomenon is known as frame dragging or the Lense-Thirring effect, after the two physicists who modeled it back in 1918. Frame dragging becomes more significant with larger masses and faster rotation, so we’ve mainly observed it around huge black holes.

Measuring how much the Earth twists spacetime as it rotates has been much more challenging because our pale blue dot of a planet is millions of times lighter than a typical black hole and rotates rather slowly.

But now, a team of astronomers led by Ignazio Ciufolini, a physicist at the Wuhan Institute of Physics and Mathematics in China, reports the most accurate measurement of the terrestrial Lense-Thirring effect to date. Their work brings our uncertainty down from a few percentage points to just 0.2 percent. And they did it with a satellite that looks like a cross between a golf ball and a disco globe.

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Earth is the only planet we know of with buoyant, silica-rich continents. But, despite decades of research, geologists still don't agree on how they formed. "The continents started appearing around about four billion years ago—that's the oldest continental rock we know about,” said Tim Johnson, a geologist at Curtin University in Perth, Australia. “The Earth is four and a half billion years old, so why they started appearing then is unknown, as is the mechanism to make that continental crust."

Johnson and his colleagues are now arguing that the formation of continents on Earth was caused largely by an intense, sustained barrage of asteroid impacts that kept the early crust hot and thin enough to make buoyant continents possible. In short, the lands we live on are here because of ancient bombardment from space.

Plates and plumes

The problem with studying the formation of continents is that the geological evidence of this process is almost gone. The oldest known continental-type rocks crystallized around 4.03 billion years ago, right at the end of the Hadean eon (the earliest era in Earth’s history, spanning the first 500 million years of its existence). Rare basaltic rocks date back about 4.2 billion years, and a handful of the oldest zircon crystals push the record back to 4.4 billion years. Beyond that, there's hardly anything else. So, scientists looking into the origin of continents had to rely largely on educated guesses. “There are huge debates about what was going on in the early Earth, because the data is so scarce,” Johnson said.

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NASA’s Perseverance rover has spent five years traversing Jezero Crater looking for the chemical leftovers of whatever processes were at work on Mars billions of years ago. The rover has found organic carbon, but it has mostly been inside rocks that had to be drilled or abraded to expose it. But now, at an outcrop on the edge of an ancient river channel named Neretva Vallis, Perseverance detected complex macromolecular carbon sitting right on the rock’s surface.

“To our knowledge, that’s the shallowest detection of organic matter on Martian surface to date,” said Ashley E. Murphy, a researcher at the Planetary Institute in Tucson, Arizona, and lead author of the study of the rock, which was found at a site called Bright Angel. On Earth, this much macromolecular carbon usually suggests a biological origin. But to learn what this Bright Angel carbon is and where it came from, we might need to bring samples back to Earth.

Carbon on the rocks

The detection of Bright Angel carbon came from SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals), a UV Raman spectrometer fitted on Perseverance’s robotic arm. SHERLOC fires a deep-ultraviolet laser at a target and reads the light that bounces back at shifted energies, a signal that enables scientists to identify specific molecular bonds.

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