The Octopus “Superarm” That Smells Its Way to Sex

Male octopuses mate “at arm’s length,” using a specialized arm, the hectocotylus, to blindly deliver sperm inside the female’s mantle cavity. A new bioRxiv preprint suggests this arm is guided by chemistry, not luck. Researchers working with California two-spot octopuses showed that males can successfully mate through an opaque divider, relying solely on touch and chemical cues. Experiments revealed the hectocotylus has up to three times more chemotactile receptors and neurons than normal arms, and its suckers respond strongly to progesterone, a key female sex hormone. Similar responses in other octopus species and squid suggest a widespread mechanism. The work hints that females might subtly influence mating success and adds a crucial mechanistic layer to cephalopod sexual selection. (Science)

Gamma-Ray Halo Hints at First Direct Dark Matter Signal

An international team analyzing gamma-ray data from NASA’s Fermi space telescope reports a faint, spherical “halo” of radiation around the Milky Way’s center that closely matches predictions for dark matter. The signal, described in the Journal of Cosmology and Astroparticle Physics, appears too smooth and symmetric to come from known astrophysical sources like pulsars. Instead, it fits models in which dark matter particles annihilate and produce gamma rays, potentially offering the first direct evidence of the elusive substance that makes up most of the universe’s matter. Other researchers are cautious, noting that uncertainties in background emission could still mimic the effect. Independent reanalyses of Fermi data and observations from upcoming missions will be crucial to confirm or refute the claim. (The Guardian)

Dark Matter–Dark Energy Tug-of-War Leaves Imprint on Halo Spins

Cosmologists running high-resolution simulations have shown that if dark matter and dark energy interact, the cosmic web of galaxies would look subtly different from the standard picture. In models where dark energy exchanges momentum with dark matter, halos form with altered spin directions and alignments along filaments compared with those in ΛCDM simulations. The work, reported in Physical Review D and highlighted by Phys.org, suggests these changes could be measurable in upcoming galaxy surveys such as Euclid and the Vera C. Rubin Observatory. Detecting the predicted pattern of halo orientations would provide rare, indirect evidence about the nature of dark energy itself, or else rule out an entire class of “interacting dark sector” theories. (phys.org)

Gaia Reveals 400 ‘Sibling’ Star Cluster Families in the Milky Way

Using precise positions and motions from ESA’s Gaia mission, astronomers have identified more than 400 groups of open star clusters that appear to be “siblings,” sharing common ages and orbits through the Milky Way. The study, published in Astronomy & Astrophysics and reported by Phys.org, shows that many clusters previously thought to be unrelated are fragments of much larger star-forming complexes that later broke apart. Tracing these families backward in time lets researchers reconstruct where in the galactic disk they formed and how spiral arms and gravity have stretched them out. The work offers a new way to map the Milky Way’s star-formation history and test models of how clusters dissolve into the general stellar population. (phys.org)

NASA’s Roman Telescope Clears Harsh Tests on the Road to Launch

NASA reports that the Nancy Grace Roman Space Telescope has passed a major round of environmental testing, keeping the dark-energy and exoplanet mission on track for launch as early as 2026. The observatory’s outer structure endured intense acoustic blasts and vibration on a shaker table, simulating rocket launch. Its core, containing the telescope and instruments, spent 65 days in a thermal-vacuum chamber cycling through the extreme hot and cold conditions of deep space. Engineers say the hardware performed as expected, and the next step is integrating the two halves into a complete spacecraft. Once flying, Roman will survey billions of galaxies, hunt for exoplanets via microlensing, and probe the physics driving cosmic acceleration. (NASA)

Mars Orbiter Challenges Idea of Hidden Southern Polar Lake

New analysis of data from NASA’s Mars Reconnaissance Orbiter casts doubt on claims that a buried lake of salty water lies beneath the planet’s south polar ice cap. Earlier radar observations from ESA’s Mars Express had revealed bright reflections interpreted as possible subsurface brines. The new study, highlighted by NASA, combines MRO radar sounding with detailed topographic maps and finds that the strongest echoes line up with underlying geologic structures and layers of frozen carbon dioxide. Computer models show these materials can produce similar signals without liquid water. The result doesn’t rule out brines on Mars, but it makes this particular “lake” far less likely, refocusing astrobiological hopes on other regions and future missions. (NASA)

Gravitational-Wave Oddity Teases Primordial Black Hole Candidate

The LIGO-Virgo-KAGRA collaboration has flagged a highly unusual gravitational-wave event, S251112cm, that may involve a black hole smaller than any known stellar remnant. Space.com reports that the signal’s properties hint one merging object could have “subsolar” mass, too light to be a normal black hole or neutron star. That raises the tantalizing possibility of a primordial black hole born in the first moments after the Big Bang, a long-sought dark matter candidate. Researchers stress the candidate could still be a statistical fluke: current estimates suggest about one similar false alarm every few years. Teams are scrutinizing the data and watching for repeats; only a population of such events would turn this provocative outlier into real evidence for primordial black holes. (space.com)

Habitable Worlds Need More Than a Goldilocks Orbit

Universe Today highlights a new astrobiology preprint arguing that planetary habitability is baked in during formation, not just set by distance from the star. The team, led by Benjamin Farcy, emphasizes four early factors: bulk composition (ratios of magnesium, iron, silicon, and oxygen that control plate tectonics), the supply of volatile elements like CHNOPS, oxygen-driven “fugacity” that sets core size and magnetic field strength, and the planet’s internal heat engine from radioactivity or tides. Using the future Habitable Worlds Observatory, astronomers could infer these properties from stellar spectra, magnetic signatures, and volcanic gases. The study sketches a “Goldilocks” balance of volatiles and core size that makes Earth hospitable while leaving Mercury and Mars barren, refining targets in the search for life. (Universe Today)

Dengue Antiviral in Limbo After J&J Exit

Johnson & Johnson’s experimental dengue drug mosnodenvir has shown striking promise yet faces an uncertain future. In a human challenge trial, high daily doses prevented infection in most volunteers and sharply reduced viral loads in others, with no significant side effects. A larger field trial in South America and Asia found zero symptomatic infections among close contacts who received the high dose, versus several in placebo and lower-dose groups. The oral antiviral, which blocks replication of all four dengue serotypes, could be used to protect exposed communities and travelers, and might work as an early treatment. But J&J has shut down its infectious disease programs, halting development. Researchers are now seeking another company to license the drug and carry it forward. (Science)