Women who used estrogen-only hormone therapy later in life were less likely to develop dementia and showed fewer signs of Alzheimer’s disease in their brains, according to a large study of more than 21,000 participants. Hormone therapy use was linked to 39% lower odds of a dementia diagnosis and 35% lower odds of Alzheimer’s-related brain changes at autopsy, including amyloid plaques and tau tangles. Biomarker tests also suggested less amyloid buildup among hormone therapy users.

A large study of more than 5,500 adults over 50 found a striking combination of risk factors: abdominal obesity paired with vitamin D deficiency was linked to a 123% higher risk of death over six years. Each condition was associated with increased risk on its own, but together they appeared to create a dangerous feedback loop, with belly fat reducing the amount of vitamin D available in the bloodstream while low vitamin D may worsen inflammation and other health problems.

Orange juice may have a much bigger effect on the body than scientists once realized. Drinking it regularly appears to influence genes tied to inflammation, blood pressure, metabolism, and blood sugar control, while studies have also found improvements in cholesterol and blood vessel health. Researchers suspect natural citrus compounds such as hesperidin may be partly responsible. Even the gut microbiome may benefit.

JWST has uncovered surprising clues that Neptune’s strange inner moons may be the wreckage of an ancient cosmic catastrophe. Researchers detected clay-like minerals on Larissa, Galatea, and Neptune’s rings that form in the presence of liquid water—yet the moons themselves show no obvious water ice. The material likely came from deep inside much larger icy moons that were shattered when Triton was captured by Neptune, destroying much of the planet’s original satellite system.

Astronomers have released more than three million new spectra in a sweeping expansion that, for the first time, brings SDSS-V optical observations to the Southern Hemisphere. The data reveal everything from rare stars and glowing nebulae to hundreds of thousands of X-ray sources and supermassive black holes changing over time.

Astronomers using the James Webb Space Telescope have discovered a bizarre object from just a few hundred million years after the Big Bang that looks like an enormous star but shines far too brightly to actually be one. The mysterious red object, dubbed a “black hole star,” may contain a black hole about 100,000 times the mass of the Sun wrapped inside a dense, star-like cocoon of hydrogen roughly the size of our solar system.

Scientists may have uncovered evidence that a mammal ancestor was giving birth to live young 236 million years ago. A fossilized cynodont showed a neonatal growth line and an unusually large birth size that closely match patterns seen in modern mammals. The discovery could push the evolution of live birth back by up to 95 million years. It also raises the possibility that many supposedly “modern” mammalian traits evolved surprisingly early.

A protein inside appetite-controlling brain cells may play an important role in preventing overeating and obesity, particularly when high-fat foods are readily available. Unexpected differences between males and females could also help explain why obesity risk—and responses to weight-loss drugs—can vary.

Why do we keep making the same choices even when better options are available? Researchers found that simply repeating a decision can reshape what we prefer, causing familiar choices to feel better than alternatives. Instead of weighing every option from scratch, the brain often remembers what it chose before and repeats it. That shortcut may help explain many everyday habits and seemingly irrational decisions.

A single human brain cell may be far more powerful than scientists once realized. Researchers found that cortical neurons can perform remarkably complex computations, giving them capabilities more like tiny biological computers than simple on-off switches. This could help explain why the human brain supports abilities such as language, imagination, and mathematics.

Researchers have discovered that a gene linked to congenital heart disease acts like an architect for the heart cell’s DNA. Losing just one copy of TBX5 can cause the genome’s carefully folded 3D structure to unravel, disrupting the genes needed to build a healthy heart. The effects can vary from cell to cell, which may help explain why people with the same mutation develop different heart defects. The same hidden mechanism could also play a role in other birth defects.

NASA’s Perseverance rover caught a striking first from Mars: Earth disappearing behind the tiny moon Phobos. Seen from nearly 195 million miles away, our planet was reduced to a single point of light before briefly vanishing behind Phobos. The rare alignment created an unusual cosmic portrait of Earth as seen from another planet.

Researchers have found a striking new way to potentially eliminate HIV soon after infection using a one-time combination of three therapies. In newborn nonhuman primates treated within three days of exposure, the regimen—standard antiretroviral drugs, broadly neutralizing antibodies, and the experimental antibody leronlimab—completely cleared the virus, even though none of the treatments could do so alone.

Researchers have found strong evidence that original collagen can survive inside dinosaur fossils for tens of millions of years, overturning a long-standing assumption about fossilization. The discovery could unlock hidden molecular clues about dinosaur biology, evolution, and how ancient proteins managed to survive for so long.

AI has helped scientists measure the brain’s hidden cleaning system, revealing that fluid moves rapidly around its outer spaces but about 50 times more slowly through deep tissue. The discovery could eventually help researchers detect circulation problems linked to Alzheimer’s, aging, and concussions.

Researchers have found a clever new way to map a part of Earth’s upper atmosphere that is notoriously difficult to observe. Using orbital data from roughly 1,200 Starlink satellites, they reconstructed changes in atmospheric density about 500 kilometers above Earth. The approach could sharpen satellite tracking and help reduce the growing risk of collisions in increasingly crowded orbits.

Keratin extracted from sheep’s wool helped damaged bone regenerate in animals, producing tissue that was more organized and structurally similar to healthy bone than tissue grown with conventional collagen scaffolds. The discovery could turn an abundant agricultural byproduct into a promising new material for regenerative medicine.

James Webb has captured a striking new infrared view of NGC 2392, the Lion Nebula, revealing the dramatic aftermath of a dying Sun-like star. At its center, a scorching white dwarf is blasting radiation into surrounding gas and dust, carving out the nebula’s lion-like face while illuminating a sprawling “mane” of surviving dusty clumps.

The adult brain may be far better at repairing itself than scientists once believed. In mice, researchers discovered a special group of support cells called astrocytes that respond to damaged brain tissue by rebuilding lost cellular networks. Rather than simply moving into the injured area, these cells perform a remarkable maneuver: they create new nuclei and send them traveling through long cellular extensions to repopulate damaged regions.

Physicists have found a new way to peer inside one of matter’s most elusive quantum states: the Wigner crystal, where electrons stop behaving like independent particles and organize into a crystal-like pattern. By shining light on an atomically thin material cooled close to absolute zero, researchers uncovered optical signals that reveal not just where the electrons are, but how they move together.

Ordinary WiFi networks could quietly become powerful surveillance tools, allowing people to be identified without cameras, special sensors, or even carrying a connected device. Researchers showed that unencrypted signals routinely exchanged between WiFi devices and routers can be used to create radio-based images of people and recognize them within seconds. In tests involving 197 participants, the system identified individuals with nearly 100% accuracy, even from different angles and regardless of how they walked.

Scientists have created an unusually corrosion-resistant stainless steel that could replace costly titanium components used to produce green hydrogen. The breakthrough could reduce structural material costs by roughly 40 times and make seawater-based hydrogen production far more economical.

Scientists have pinpointed a brain network—and its distinctive electrical rhythm—that appears to drive the benefits of deep brain stimulation for Parkinson’s disease. The discovery could lead to more precise, personalized stimulation settings and better results for patients.

Some black holes roaming the Universe today may actually be older than the Big Bang. A new cosmic “bounce” model suggests the Universe expanded from an earlier contracting phase, allowing ancient black holes to survive the transition as cosmic fossils. These relics could potentially explain dark matter and why surprisingly massive objects appeared so early in cosmic history.

Ancient remains from Vietnam suggest diseases like yaws may have been passed from mother to child thousands of years ago, a form of transmission often assumed to indicate syphilis. The discovery could overturn how scientists interpret ancient infections and complicate the long-running mystery of syphilis’s origins.

MIT neuroscientists have found striking evidence that language and logical reasoning are powered by separate systems in the brain. Even people with severe language impairments caused by stroke were able to solve challenging logic puzzles as well as people without those impairments, while brain scans showed that language-processing regions stayed largely quiet during reasoning tasks.

Ozempic-like drugs appear to weaken more than hunger—they may also reduce cravings for alcohol and other addictive substances. Scientists are increasingly tracing this effect to the lateral septum, a brain region that helps connect memories and surroundings with rewarding experiences. Packed with GLP-1 receptors, it may act as a crucial control point between thinking about a reward and feeling compelled to pursue it. The discovery could open new approaches to treating addiction as well as obesity.

Scientists probing life’s deepest origins have uncovered evidence that the first free-living cells may have emerged not once, but twice. The findings suggest a striking possibility: life may share one ancient genetic code, yet have undergone two separate transitions into free-living existence.

Dogs may understand our emotions more deeply than scientists realized. Brain scans show that happy human faces activate regions in dogs linked to higher-level processing and reward, suggesting that smiles carry special emotional significance for them.

A forgotten fragment of a lost papal letter is offering a surprising new explanation for the Norman Conquest. England may have backed the wrong pope during a bitter religious power struggle, giving Pope Alexander II a political reason to support William the Conqueror’s invasion. The discovery suggests Harold’s downfall in 1066 was shaped by intrigue in Rome as well as bloodshed at Hastings.