NASA Rules Out a 2032 Moon Strike for Asteroid 2024 YR4: NASA says new James Webb Space Telescope observations have effectively closed the book on worries that near-Earth asteroid 2024 YR4 might hit the Moon on December 22, 2032. The new data, collected on February 18 and 26, let experts at JPL refine the asteroid’s orbit enough to rule out impact entirely. Instead, NASA now expects the object to pass about 13,200 miles from the lunar surface. The agency stressed that this is not because the asteroid “moved,” but because our estimate of where it will be became much more precise. The observations were also technically notable: NASA described them as among the faintest asteroid observations Webb has ever made, highlighting the telescope’s growing value for planetary defense as well as deep-space astronomy. (NASA Science)
DART’s Impact Changed More Than One Orbit: NASA’s DART mission already proved that humanity can alter an asteroid’s motion by slamming a spacecraft into it. Now researchers say the 2022 impact did even more than shorten Dimorphos’s orbit around Didymos: it also changed the binary system’s orbit around the Sun. According to NASA, the collision ejected so much debris that the system’s solar orbit shifted by about 0.15 seconds, a tiny amount but still a measurable one. Scientists estimate the momentum boost from the escaping debris roughly doubled the effect of the spacecraft’s impact alone. That matters because planetary defense is all about small changes made early. Over long timescales, a tiny tweak in an asteroid’s motion can spell the difference between a future hit and a clean miss, which makes this latest DART result more practically important than it first sounds. (NASA)
ESA Watches a Solar Superstorm Slam Into Mars: A new ESA-backed study describes what happened when the huge May 2024 solar storm reached Mars, and the answer is: a lot. Data from Mars Express and the ExoMars Trace Gas Orbiter show the planet’s upper atmosphere was flooded with electrons, with densities soaring by 45% in one layer and 278% in another. ESA says the orbiters also experienced computer glitches, though both recovered quickly because they were designed for radiation hazards. One of the most interesting parts of the story is methodological: the team used orbiter-to-orbiter radio occultation, in which a radio signal is bent by Mars’s atmosphere and used to reconstruct its structure. ESA calls it a relatively new way to study Mars in real time. Beyond the drama, the result is a vivid reminder that space weather behaves differently on worlds without Earth’s magnetic shielding. (European Space Agency)
Gravitational Waves May Offer a New Route Through the Hubble Tension: One of cosmology’s biggest headaches is the “Hubble tension,” the stubborn mismatch between different measurements of how fast the universe is expanding. A new proposal highlighted by Space.com suggests that gravitational waves could provide a third, independent way to estimate the Hubble constant. Instead of relying on individual merger events alone, researchers want to use the background “hum” produced by countless black hole mergers across the universe — what they call a stochastic siren method. The idea is that different expansion rates imply different cosmic volumes and therefore different strengths for the gravitational-wave background. Current detectors are not yet sensitive enough to settle the matter, but the team says the method already works as a proof of concept and could become far more powerful as LIGO-Virgo-KAGRA improves over the next several years. (Space)
Astronomers Find an Absurdly Tight Quadruple Star System: Astronomers using TESS have found what Space.com describes as the most compact known “3+1” quadruple star system, a rare arrangement in which three stars form a tight inner grouping while a fourth orbits farther out. The system, TIC 120362137, is so jam-packed that it could fit within the span between Jupiter and the Sun. Researchers were able not only to identify the architecture but also to model its future evolution, giving the discovery extra value as a laboratory for stellar dynamics. Multiple-star systems are not unusual in the galaxy, but extremely tight, well-characterized quadruples are much rarer and harder to pin down. That makes this one useful for testing ideas about how stars form, exchange angular momentum, and evolve in crowded gravitational environments where even small orbital changes can trigger dramatic long-term outcomes. (Space)
A Ground-Based Path to Seeing Earth-Like Exoplanets?: A paper featured by Phys.org argues that observing Earth-like exoplanets may not require waiting for a giant dedicated space telescope. Instead, the researchers propose pairing a huge ground-based telescope with a shared orbiting starshade that blocks a host star’s glare before its light reaches Earth. The concept, published in Nature Astronomy, would in principle let astronomers use an aperture far larger than NASA’s planned Habitable Worlds Observatory while still suppressing the starlight that usually drowns out a small rocky planet. The idea is still conceptual rather than mission-ready, but it offers a provocative shift in strategy: rather than building everything into one ultra-expensive space observatory, future planet hunters might divide the job between ground and orbit. If it works, it could broaden the search for habitable worlds and speed up the path toward directly imaging Earth analogues. (Phys.org)
TOI-5734 b Is a Hot Sub-Neptune Sitting Near the Radius Valley: Astronomers have confirmed a new exoplanet, TOI-5734 b, using data from TESS and the HARPS-N spectrograph, and it looks like a particularly interesting occupant of the so-called radius valley. Phys.org reports that the planet is about 2.1 times Earth’s radius and 9.1 times Earth’s mass, orbiting a relatively young K dwarf about 106 light-years away every 6.18 days. Its density is only slightly lower than Earth’s, which suggests it may be a rocky world that has already lost most of its primordial atmosphere. Researchers say it may continue shedding what remains over the next 300 million years. That makes TOI-5734 b useful not just as another entry in the exoplanet census, but as a case study in how close-in planets evolve from gas-rich worlds into stripped-down, denser remnants. (Phys.org)
JUICE Catches an Interstellar Comet in Flight: A Jupiter-bound spacecraft has turned into an interstellar visitor photographer. Scientific American highlighted new imagery of comet 3I/ATLAS captured by the JANUS camera aboard ESA’s JUICE mission, giving astronomers one more angle on a rare object that originated beyond our solar system. The comet shot between the orbits of Earth and Mars late last year and reached speeds above 150,000 miles per hour near perihelion, making it one of those fleeting targets that scientists scramble to study before it vanishes back into interstellar space. The new observations matter because every interstellar body carries clues about the chemistry and dynamics of another planetary system. We have seen only a handful of these objects, so each fresh image and spectrum is disproportionately valuable. This one extends JUICE’s scientific resume before it even reaches Jupiter. (Scientific American)
Fresh Evidence Points to Lightning on Mars: Mars may be electrically livelier than it looks. Scientific American reports that two NASA missions — MAVEN in orbit and Perseverance on the surface — have picked up very different kinds of signals consistent with lightning on the Red Planet. That does not mean Mars has Earth-like thunderstorms; the article emphasizes that any martian lightning is probably harder to detect and may arise in very different atmospheric conditions, including dust-driven activity. Still, the convergence of orbital and surface evidence makes the case more compelling than before. The story matters scientifically because lightning is tied to atmospheric chemistry, dust behavior, and electrical processes that shape a planet’s near-surface environment. On Mars, where the atmosphere is thin and dust is everywhere, understanding whether lightning exists — and under what conditions — could sharpen models of weather, hazards, and even the interpretation of strange radio or chemical signals. (Scientific American)
Crystals Older Than the Sun Reopen the Solar System’s Origin Debate: Quanta’s excellent new piece looks at presolar grains — microscopic crystals locked inside meteorites that are older than the Sun itself — and how they are reshaping debates over the solar system’s birth. For decades, the standard story held that a nearby supernova both seeded the young solar nebula with aluminum-26 and triggered its collapse. But newer measurements, especially of iron-60, have complicated that picture. If the early solar system had been heavily influenced by a supernova, researchers argue, it should show more of iron-60 than it seems to. That has pushed some scientists toward an alternative: that winds from a massive Wolf-Rayet star delivered aluminum-26 without the same iron signature. The presolar grains now being studied may help distinguish between those scenarios, turning meteorites into time capsules from before the Sun even ignited. (Quanta Magazine)