A new mathematical method could make long-term simulations of binary asteroids more reliable by preventing energy and rotational errors from building up. The method treats an asteroid pair’s position and rotation together, which becomes especially important when irregular shapes affect their mutual gravity. Tests showed the approach preserved key physical properties better than standard Runge–Kutta calculations while also reducing computational costs. Binary asteroids can behave less like two simple rocks in orbit and more like a tightly coupled mechanical system. Their shapes, positions and rotations all influence one another, making long-term predictions difficult and exposing weaknesses in standard numerical methods. That problem matters because binary systems may account for about 16% of identified near-Earth asteroids. Accurate modeling could support both impact-threat assessment and future exploration of small bodies. Instead of treating orbital motion and rotation as separate problems, the method keeps them in one geometric framework. That matters when the bodies are irregular, because gravity depends not only on where each object is, but also on how each one is oriented. A two-body problem with …

A major limit on dark photon dark matter may be far weaker because early-universe plasma stops absorbing energy much sooner than expected. Computer simulations show that plasma becomes unstable as energy builds, disrupting the resonance that was supposed to produce substantial heating. The result reopens about 10 orders of magnitude in dark photon mass for experiments and may force physicists to reconsider similar limits in other astrophysical environments. For years, one of the strongest cosmological arguments against dark photon dark matter rested on a simple idea: if dark photons converted into ordinary light in the early universe, they should have heated cosmic plasma enough to leave measurable traces. That assumption may not hold. A team from Perimeter Institute and the University of Maryland reports that the conversion process can trigger powerful nonlinear effects in plasma. Those effects quickly disrupt the resonance that drives energy transfer, shutting the process down before much heating occurs. The result weakens some of the strongest cosmological limits on dark photon dark matter across about 10 orders of magnitude in mass, …

High-energy particles in radiation belts can look as if they are spreading randomly even when their underlying motion remains predictable. A moving spacecraft can lose sight of fine particle structures because neighboring particle groups circle a planet at slightly different speeds. The ambiguity could affect radiation-belt models and strengthens the case for missions using several spacecraft to observe the same region at once. High-energy particles trapped in Earth’s radiation belts can look as if they are spreading randomly, even when their motion is fully predictable. The problem may lie not in the particles, but in how spacecraft see them. Radiation belts are doughnut-shaped zones of energetic particles held by magnetic fields. Earth has them, but so do Jupiter, Saturn and Jupiter’s moon Ganymede. Similar belts have also been detected around ultracool brown dwarfs. For decades, scientists have often interpreted the smoothing of particle populations as evidence of radial diffusion, a process in which particles gradually spread across magnetic regions through repeated interactions with fluctuating electric and magnetic fields. The new analysis shows that another process …

A thin ribbon of stars around the ultra-diffuse galaxy UGC 9050-Dw1 may be the first globular-cluster stellar stream identified beyond the Milky Way. Its shape allowed astronomers to reconstruct the galaxy’s gravity and estimate how much dark matter surrounds it. Deeper observations are still needed to confirm the stream’s origin, but future space telescopes could uncover many more examples. A faint arc only about 72 parsecs wide is peeling away from a star cluster 115 million light-years from Earth. If the interpretation holds, it gives astronomers a new way to map dark matter far beyond the Milky Way. The feature lies in UGC 9050-Dw1, an ultra-diffuse galaxy with a sparse population of stars. Astronomers named the arc Oyashio, after a cold Pacific Ocean current. It stretches about 2 kiloparsecs from a globular cluster candidate roughly 2.5 kiloparsecs from the galaxy’s center. Globular clusters are dense collections of stars held together by gravity. As one circles a galaxy, tidal forces can pull stars from its edges. The escaped stars keep moving along similar orbits, creating thin …

IceCube has produced the first neutrino image of the Milky Way, revealing high-energy particle activity concentrated along our galaxy’s plane and center. Deep-learning tools let researchers identify more than 20 times as many useful events, pulling the faint galactic signal from an enormous background. The signal strongly supports the Milky Way as a source of high-energy neutrinos, but researchers still cannot pinpoint individual sources or determine which emission model is correct. The Milky Way has long been mapped in starlight, radio waves and gamma rays. Now it has appeared in an entirely different form: a ghostly image traced by high-energy neutrinos, with the strongest signal concentrated toward the galaxy’s center. The image comes from 10 years of observations by the IceCube Neutrino Observatory at the South Pole. The results, published in Science, provide strong evidence that the Milky Way itself produces high-energy neutrinos. Members of the IceCube Collaboration at Stockholm University and Uppsala University helped analyze the data. Their work suggests cosmic-ray interactions near the Galactic Center may be more intense than earlier models predicted. …

A galaxy simulation shows that nuclear star clusters and nuclear stellar disks can grow together as a stellar bar funnels gas toward the galactic center. Repeated shocks from stellar feedback move gas inward and trigger new star formation, while the surrounding nuclear disk gradually expands from the inside out. The connection can become difficult to recognize as the two structures evolve at different rates, and mergers with massive star clusters can further reshape the galactic center. At the heart of a barred galaxy, two stellar structures can grow around the same central region. One is compact and pressure-supported. The other spreads outward as a rotating disk. Their apparent disconnect has obscured a shared origin. A simulation from the SMUGGLE-Ring project shows how both structures can emerge together in a Milky Way-mass galaxy. It examines nuclear star clusters, or NSCs, and nuclear stellar disks, or NSDs. Observational surveys have found no clear correlation between their masses and sizes, reinforcing the idea that they form separately. The work follows their development over four billion years. A stellar …

A photon can cross a billion light-years while accumulating no elapsed time along its path. Special relativity links space and time, causing moving clocks to run more slowly as their speed increases. The same physics affects aircraft clocks, GPS satellites, gravitational lensing, and the limits of cause and effect. A photon crossing a billion light-years experiences no elapsed time, even though its journey spans a billion years on Earth. That result comes directly from special relativity and exposes how differently the universe treats light, motion, and time. Time is not a universal background shared by every object. It depends on speed, location, and the path an object takes through spacetime. Two clocks return with different answers The clearest demonstration begins with two identical atomic clocks. They are synchronized side by side, then separated. One stays put while the other travels aboard a fast aircraft before returning. When the clocks meet again, the traveling clock shows slightly less elapsed time. The difference is tiny, but modern atomic clocks can measure it. Physicists Joseph Hafele and Richard …

A meteorite 50 to 200 times more massive than the one linked to the dinosaurs struck Earth 3.26 billion years ago. The impact triggered a tsunami, ocean heating and darkness, but it also carried phosphorus and moved iron-rich deep water toward the surface. Those nutrients may have helped iron-using microbes recover quickly, showing that early impacts could support life as well as destroy it. A meteorite far larger than the one linked to the dinosaurs struck Earth 3.26 billion years ago, yet the devastation may have briefly created better conditions for some of the planet’s earliest microbes. The S2 impactor measured an estimated 37 to 58 kilometers across and carried 50 to 200 times the mass of the Chicxulub object. Its collision unleashed a tsunami, heated the atmosphere, disturbed the oceans and darkened the surface with dust. Rock layers in South Africa’s Barberton Greenstone Belt record what followed. The evidence points to a disaster that damaged shallow-water life, then supplied iron and phosphorus that may have fueled a rapid microbial rebound. A tsunami rewrote the …

Astronomers captured the clearest evidence yet that another star orbits Betelgeuse. The likely companion appears two to three times heavier than the Sun and may circle Betelgeuse about once every six years. More observations are needed to confirm its orbit and learn whether it affects Betelgeuse’s dimming, evolution, or eventual supernova. A faint point of light sits beside Betelgeuse in a newly processed image. It may resolve a century-old question about the famous red supergiant, while opening another about how its unseen partner could shape the star’s final years. “This is the conclusion of a century-long quest,” said Montargès, an astronomer at the Observatoire de Paris-PSL in France. Betelgeuse lies in the constellation Orion and is easily visible without a telescope. Its reddish color, changing brightness, and eventual fate as a supernova have made it one of the most closely watched stars in the sky. A predicted opening beside Betelgeuse Astronomers have repeatedly proposed that Betelgeuse has a companion, but earlier claims lacked independent confirmation. Interest intensified after researchers connected the star’s longest brightness cycle …

A clock aboard a fast-moving spacecraft does not break, lag or malfunction. It ticks normally for everyone inside. Hearts beat, coffee cools and hair grows at the usual pace. Yet when the travelers return, they may have aged far less than people who stayed on Earth. That unsettling result does not come from radiation, weightlessness or some hidden effect of space travel. It comes from the structure of time itself. According to special relativity, observers moving at different speeds can experience different amounts of time between the same events. The idea sounds remote until you consider that nothing is ever truly still. Earth moves around the sun at roughly 30 kilometers per second. The sun circles the Milky Way at about 230 kilometers per second. The galaxy moves through the universe at hundreds of kilometers per second more. Those speeds do not provide a universal measure of motion. Physics offers no fixed background against which everything else can be judged. Motion only has meaning relative to another object. No observer owns the correct viewpoint Place …