Latest news with #AmericanAstronomicalSociety
Yahoo
21 hours ago
- Science
- Yahoo
NASA raises chance for asteroid to hit the moon
June 19 (UPI) -- NASA has announced that an asteroid about 200 feet in diameter is now slightly more likely to crash into the moon. According to the newest data collected, NASA's Center for Near-Earth Object Studies at the agency's Jet Propulsion Laboratory has refined the expected course for Asteroid 2024 YR4 and has given it an increased 4.3% probability of striking the moon on Dec. 22, 2032. The original likelihood was at 3.8% probability. The space rock is too far off in space to be detected with ground telescopes, but the James Webb Space Telescope, which orbits the sun, was able to take a new look at the space rock earlier this month before it was obscured from view. It was that opportunity that provided the data that led to the changed forecast. Due to YR4's solar orbit, NASA won't be able to view it again until it comes back around the sun in 2028. According to a research paper submitted to the American Astronomical Society journals and published Monday, should the asteroid hit the moon, it could cause a crater as large as around 3,200 feet and release 6.5 megatons of energy. As much as 220 million pounds of lunar material could be released by such an impact, and then as much as 10% of that ejecta could fall to Earth a few days later, so "meteorites are unlikely, though not impossible" according to the paper, but it would create an "eye-catching" meteor shower. However, any moon bits that do come toward the Earth also could increase the meteoroid impact exposure faced by satellites in near-Earth orbit for as long as a decade.
Yahoo
21 hours ago
- Science
- Yahoo
Tiny galaxies may have helped our universe out of its dark ages, JWST finds
When you buy through links on our articles, Future and its syndication partners may earn a commission. Evidence continues to assemble that dwarf galaxies played a larger role in shaping the early universe than previously thought. Astronomers analyzing data from the James Webb Space Telescope (JWST) have uncovered a population of tiny, energetic galaxies that may have been key players in clearing the cosmic fog that shrouded the universe after the Big Bang. "You don't necessarily need to look for more exotic features," Isak Wold, an assistant research scientist at the Catholic University of America in Washington D.C., told reporters during the 246th meeting of the American Astronomical Society in Alaska. "These tiny but numerous galaxies could produce all the light needed for reionization." About 380,000 years after the Big Bang, the universe cooled enough for charged particles to combine into neutral hydrogen atoms, creating a thick, light-absorbing fog, an era known as the cosmic dark ages. It wasn't until several hundred million years later, with the birth of the first stars and galaxies, that intense ultraviolet (UV) radiation began reionizing this primordial hydrogen. That process gradually cleared the dense fog, allowing starlight to travel freely through space and illuminating the cosmos for the first time. For decades, astronomers have debated what triggered this dramatic transformation. The leading candidates included massive galaxies, quasars powered by black holes, and small, low-mass galaxies. New data from the JWST now points strongly to the smallest contenders, suggesting these tiny galaxies acted like cosmic flashlights lighting up the early universe. To identify these early galaxies, Wold and his colleagues focused on a massive galaxy cluster called Abell 2744, or Pandora's Cluster, located about 4 billion light-years away in the constellation Sculptor. The immense gravity of this cluster acts as a natural magnifying glass, bending and amplifying light coming from much more distant, ancient galaxies behind it. Tapping into this quirk of nature, combined with the JWST's powerful instruments, the researchers peered nearly 13 billion years back in time. Using the JWST's Near-Infrared Camera (NIRCam) and Near-Infrared Spectrograph (NIRSpec), the team searched for a specific green emission line from doubly ionized oxygen, a hallmark of intense star formation. This light was originally emitted in the visible range but was stretched into the infrared as it traveled through the expanding universe, according to a NASA statement. The search yielded 83 tiny, starburst galaxies, all vigorously forming stars when the universe was just 800 million years old, around 6% of its current age. "Our analysis [...] shows they existed in sufficient numbers and packed enough ultraviolet power to drive this cosmic renovation," Wold said in the statement. Today, similar primitive galaxies, such as so-called "green pea" galaxies, are rare but known to release roughly 25% of their ionizing UV radiation into surrounding space. If early galaxies functioned in the same way, Wold said, they would have generated enough light to reionize the hydrogen fog and make the universe transparent. "When it comes to producing ultraviolet light, these small galaxies punch well above their weight," he said in the statement.
Yahoo
12-06-2025
- Science
- Yahoo
'Uranus is weird.' Big moons of tilted ice giant hide a magnetic mystery, Hubble telescope reveals
When you buy through links on our articles, Future and its syndication partners may earn a commission. New data from the Hubble Space Telescope suggests that Uranus' largest moons are gathering dust — literally. Uranus, the seventh planet from the sun and home to 28 known moons, is well known for its bizarre tilt. The planet spins almost completely on its side, an oddball orientation that twists its magnetic field into a warped and constantly shifting force, which scientists have long thought would leave visible scars on its moons by bombarding them with charged particles. However, new Hubble Space Telescope observations of Uranus' four largest moons — Ariel, Umbriel, Titania and Oberon — show no clear signs of the expected radiation damage, Christian Soto of the Space Telescope Science Institute in Maryland, who led the analysis, told reporters on Tuesday (June 10) at the 246th American Astronomical Society (AAS) press conference in Alaska. Based on data from NASA's Voyager 2 flyby in 1986 and decades of modeling, scientists expected the trailing hemispheres of Uranus' moons — the sides opposite their direction of travel — to be visibly darkened by radiation. The leading sides, by contrast, were expected to remain relatively brighter. Instead, the researchers found that the two outer moons, Titania and Oberon, are darker on their leading sides, the opposite of what they had predicted. The visible darkening, they say, doesn't come from Uranus' magnetic field at all, but from dust. Hubble's data points to a slow inward drift of dust from Uranus' distant irregular moons, which orbit between 2.5 to 13 million miles (4 to 20 million kilometers) from the planet. These outer moons are constantly bombarded by micrometeorites, which kick up particles that gradually spiral inward over millions of years, Soto said. As Titania and Oberon travel through this diffuse dust cloud, they accumulate the particles mostly on their leading sides. "Think of driving very fast on a highway, and bugs are hitting your windshield — that's what we're seeing here," Soto said during the press briefing. Interestingly, the inner moons Ariel and Umbriel show no significant difference in brightness between their leading and trailing sides — possibly because the drifting dust doesn't reach them, thanks to shielding by Titania and Oberon. "Dust collection — I didn't even expect to get into that hypothesis," Richard Cartwright, a planetary scientist at the Johns Hopkins University's Applied Physics Laboratory in Maryland, said in a statement. "But you know, data always surprise you." As for the role of Uranus' powerful magnetic field, researchers now suspect that its effects might be subtler or more complex than previously thought. It may still be interacting with the moons, but not in a way that creates strong contrasts on their surfaces. RELATED STORIES: — Uranus: Everything you need to know about the coldest planet in the solar system — Are there hidden oceans inside the moons of Uranus? Their wobbles could tell us — A day on Uranus is actually longer than we thought, Hubble Telescope reveals "Uranus is weird, so it's always been uncertain how much the magnetic field actually interacts with its satellites," Cartwright said in the statement. The findings highlight how little we still know about Uranus. Apart from Voyager 2's brief flyby nearly 40 years ago, coincidentally during a rare solar event, no dedicated mission has ever visited the planet. To learn more, Soto's team has scheduled follow-up observations with the James Webb Space Telescope within the next year. Using infrared imaging, Webb will take a closer look at the same moons, potentially confirming whether dust, radiation or a combination of both is shaping their surfaces. "Why do we do this?" Soto said at the briefing. "Well, Uranus is weird — so why not?"
Yahoo
31-05-2025
- General
- Yahoo
Does extraterrestrial life smell like the sea?
Dimethyl sulfide, also known as DMS, sounds like it could be a chemical compound you'd try to avoid on an ingredient label, or the poisonous ingredient in a murder mystery. But some scientists view this simple compound as a biosignature — a key indicator of life. So there was great excitement when DMS was discovered on a "sub-Neptune planet" far from our solar system – 124 light years away, or about 17 trillion miles, in the constellation Leo. 'We want to be a bit careful in claiming any evidence of life at this stage,' cautioned lead author Nikku Madhusudhan, of Cambridge University, about the findings he published last month in The Astrophysical Journal Letters, a publication of the American Astronomical Society, with other researchers from two American space institutes and two British physics and astronomy departments. 'We have to look at a lot more molecules, and we have, and we couldn't come up with a much better explanation,' Madhusudhan told Salon in a video interview. He admits he can't be 100% certain that dimethyl sulfide, or (CH3)2S, exists on the planet called K2-18 b. But it looks very likely, as last month's research built on a paper published in 2023 that also found suggestions of DMS on the same planet but relied on different evidence. But why would a random compound detected on a planet so far beyond our reach be a strong indicator of life? Well, let's consider the story of DMS on Earth, a story of the strange and poetic ways life appears and reappears in different guises — and with different scents. Dimethyl sulfide is the largest natural source of atmospheric sulfur on Earth, which means that it gets into the atmosphere and cycles around. But it starts its journey in the ocean. You're absolutely familiar with DMS, even if you've never heard of it before. It's the source of the smell of the sea, that sort of fishy, sort of eggy aroma that evokes deeply nostalgic reactions in, well, almost everyone. Interesting pushback came from Christophe Laudamiel, a master perfumer at Generation by Osmo. 'I have personally never used that ingredient for the smell of the sea,' he told Salon by email. 'It would be rather used for 'hot' smells and for ripe to overripe smells." He compared the odor of DMS to "fish that stayed too long in the sun," adding, quite understandably, that "we usually avoid" such associations "when we recreate the smell of the sea in perfumery." Rather than relying on those fish-rotting-in-sun odors to get ocean-smelling perfume, suggested Generation by Osmo founder and CEO Alex Wiltschow (also by email), "We combine aquatic notes with mineral wet stone notes, salty notes and clean air notes," along with, perhaps, "a touch of seaweed absolute as well or mossy top notes." Similarly environment-evoking are the substances geosmin and petrichor. Petrichor is the pleasant, earthy aroma of rain falling on dry soil, sometimes described more simply as the smell of rain. That word has almost become trendy. In fact its use appears to have skyrocketed in the past quarter-century, though it was coined in the journal Nature in 1964. Like geosmin, the substance that gives earth its characteristic "earthy" odor, petrichor remains close to the ground. Dimethyl sulfide, however, gets around. The DMS that cycles around our world is produced, for the most part, by marine organisms, most notably the microscopic plants known as phytoplankton that live in the nutrient-rich upper layer of the ocean. These tiny organism exist in abundance, which is why DMS is responsible for most of that smell we associate with the seaside. From the surface layer of the Earth's oceans, DMS, which is a volatile chemical, escapes into the air, joining the atmospheric cycling of sulfur. As one researcher describes this process, once in the atmosphere DMS "has other major effects, being the 'seed' that sets off cloud formation over the oceans. Indeed, the production of this molecule is on such a scale that it has major effects on the world's climate, thanks to its effect on the cloud cover over the oceans.' That quotation is nearly 20 years old, but scientists still don't know exactly to what extent DMS is responsible for seeding clouds, just that it's a significant factor. The tiny aerosol particles formed when DMS molecules are zapped by sunlight and other molecules in the atmosphere, which become the 'seeds' for clouds, also exert meaningful effects on our climate by reflecting sunlight back into space. In 2007, scientists at the University of East Anglia discovered that a single gene could produce dimethyl sulfide from dimethylsulfoniopropionate, or DMSP, the food that phytoplankton eat. As described in a paper in Science, you can take that gene, which has the catchy name dddD, from bacteria that live in the sea, or find it in other species of bacteria that hang out with plants instead but also produce DMS. Once you've found a bacterium with the dddD gene, you can clone it and stick it into an bacterium, which will then happily produce dimethyl sulfide. The aforementioned predecessor chemical DMSP is found, by the billions of tons, all over the world's oceans, seas and seashores. Marine plants and phytoplankton use it to protect themselves from the saltiness of seawater, literally as a buffer against stress. When these tiny plants die, some of their DMSP becomes available, as food for other bacteria. Terrestrial plants may also have symbiotic bacteria living in their root systems, which produce dimethyl sulfide from the DMSP released when their hosts die. This process — one kind of organism dies, offering sustenance to others — is how this cycle begins, at least on Earth. (If you can actually say that a cycle has a beginning or an end.) As one of the East Anglia scientists, Andrew Johnston, wrote in a 2007 project funding proposal, describing the role of DMS in seeding clouds, its importance has been known since 1971, "with some 30 million tons of it being liberated into the air, worldwide, every year.' Aquatic bird species such as sea petrels and shearwaters are attracted to the ripe-fish aroma, while Johnston later discovered that the Atlantic herring has strains of bacteria in its gut microbiome called Pseudomonas and Psychrobacter, which digest DMSP and break it down into, yes, dimethyl sulfide. How did those bacteria get inside a fish? Herring eat small plants known as mesozooplankton, which themselves eat the much smaller phytoplankton. This familiar ecological pattern — bigger creatures eating smaller creature — has internalized the production of this evocative and volatile to the food chain, it seems, the creation dimethyl sulfide can take place not just in the surface layer of the ocean, but inside herring guts as well. Herrings are vertebrates, in the greater evolutionary scheme not all that different from us. Does this mean that humans also have the potential to create sulfurous stinks from our own insides? Well, there's no evidence at this point that our microbiomes contain DMS-producing bacteria. But that's ok. As you may be aware, our species can produce our own glorious forms of stink. Dimethyl sulfide is an essential element in the characteristic odors of blood, serum, tissues, urine and breath in people (and rats). Not to mention the distinctive smell of feces and flatus, i.e., farts. Let's mention here that dimethyl sulfide is emitted during wildfires, and so contributes to a scent that has grown chillingly familiar in many parts of North America in recent years. It's also largely responsible for the smell of the delicately-named dead horse arum, a relative of the so-called corpse flower, or titan arum. Other flowers with unappetizing odors use different chemicals as their top notes, all with the purpose of attracting pollinators drawn to the aroma of their preferred type of rotting meat. Here for example is Wikipedia's almost lyrical rundown of the various sources of the corpse flower's scent: 'Analyses of chemicals released by the spadix show the stench includes dimethyl trisulfide (like limburger cheese), dimethyl disulfide (garlic), trimethylamine (rotting fish), isovaleric acid (sweaty socks), benzyl alcohol (sweet floral scent), phenol (like Chloraseptic), and indole (like feces).' Scientists comparing the molecules involved in producing the stench of dead horse arum with those produced by a rotting corpse found that dimethyl sulfide was associated with the middle stage of decomposition in actual corpses (to be clear, this involved dead mice, not dead horses or human cadavers). All this odoriferous research has convinced some scientists that DMS is intimately associated with life, making it an ideal biosignature if found hundreds of light years away on some lonely planet. Critics of Madhusudhan's findings point out, however, that dimethyl sulfide can exist without demonstrating life at all. For one thing, you can make it in a lab. As the perfumer Laudamiel told Salon, DMS is "often used in perfumery, but not for its low-tide, rotten egg facet.' The human nose can detect one part per million of DMS, as an unpleasant, cabbage-like smell used, for example, to add a warning signal to the poisonous gas carbon monoxide, which is otherwise odorless natural gas. DMS also results from kraft pulping, producing a ghastly, retch-inducing smell you'll have noticed if you've ever driven by a paper processing plant. It's produced naturally as bacteria do their work on dimethyl sulfoxide waste in sewers. When it's not saving us from asphyxiation or carrying out useful industrial processes, dimethyl sulfide also lends its "low-tide, rotten egg facet" as a nearly subconscious flavor in food and drinks, measured in a few parts per million. In brewing certain lagers, though, breweries may want that slightly funky flavor, and add enough DMS to cross the flavor threshold as a hint of the ocean (or of distant rotten eggs, or cabbage). The natural production of DMS is also medically useful. It turns out that as a kind of bacteria turns from existing peacefully in our mouths to causing colon cancer in our nether regions, it produces dimethyl sulfide. Worsening osteoporosis in older women may lead to exhaling DMS, as can the positive effects of a medication cocktail for children with cystic fibrosis. But how is it that the compound that gives us the glorious smell of the sea — and just perhaps, our first evidence of life on a distant planet — also provides the generally disagreeable fragrance of flatus, feces and flowers that smell like rotting meat? 'It works just like salt in a cake," explained Laudamiel. "In combination with other molecules, at low, unrecognizable dosages, it brings out the flavors of other facets." Unpleasant-sounding flavor notes such as "the overripe 'vomity' note found naturally in papaya ... the 'feet' note found in Parmigiano or the 'sweaty' note found naturally in dark chocolate" produce magical effects in combination with others and in just the right amount. Remove those notes, he concluded, and your papaya, cheese or chocolate will "taste much less yummy." Indeed, DMS, provided by nature at just the right dosage, is a component in the much coveted scent of truffles. Turning away from our planet with its stinky-feet cheese, vomity papayas and sweaty chocolate, and turning to the stars, DMS is used as an additive in rocket fuel, added to ethylene oxide to prevent exhaust nozzles getting dirty and stop carbon building up on firing-chamber surfaces. But no existing or planned spacecraft can get us anywhere near the next possible known source of dimethyl sulfide on K2-18 b, the planet where Madhusudhan and colleagues have found, thanks to the James Webb Space Telescope, what they think could well be this signature of life. Astronomers these days are really interested in sub-Neptune planets, meaning those with diameters larger than Earth but smaller than Neptune. It's an exotic niche that doesn't exist in our solar system, and could offer new possibilities for finding life. They're particularly interested in a newly-defined type of planet that could exist within that range: Hycean worlds, which would possess water-rich interiors, planet-spanning oceans and atmospheres rich in hydrogen gas. The Madhusudhan team's detection of methane and carbon dioxide gases on K2-18 b supports his argument that the planet might have surface water, as does the fact that they did not find ammonia, which is soluble in water — if that's detected in the atmosphere, there probably isn't an ocean. But while DMS is a biosignature here on Earth, other scientists point out that it could be cooked up by some other process elsewhere, just as it can be produced in a laboratory for industrial purposes. Some scientists have suggested other possible explanations for the signals found by Madhusudhan's team, including statistical noise. Two findings within the past year bolster these criticisms. One, described last October, is the presence of dimethyl sulfide in a comet named 67P/Churyumov-Gerasimenko, which no one would argue suggests biological activity. Madhusudhan says that does nothing to disprove his hypothesis; comets are known to be little laboratories that can cook up all sorts of unlikely things. 'The same comet also has molecular oxygen in it, right?' he countered. 'It also has methane and other molecules, including amino acids." Finding something in a comet, he said, "doesn't mean that it can't be a biosignature in a planetary atmosphere, because those are two very different environments." Another finding that may cast doubt on the idea that DMS equates to the presence of life is the discovery of dimethyl sulfide, which here on Earth makes the sea smell like the sea, drifting around in deep space between the stars. Reporting on the open science platform Arxiv in February, an international group of astronomers said they found DMS during an ultra-deep molecular line survey, which uses fancy telescopes to look at a spectrum of wavelengths in one particular stretch of outer space and then catalog its chemical composition and physical properties, such as temperature and density. In this case, they pointed their telescopes toward a Galactic Center molecular cloud named G+0.693-0.027. And there they found dimethyl sulfide, just vibing in the void.
Forbes
31-05-2025
- General
- Forbes
Scientists: Webb Telescope May Find Planet Around Closest Bright Star
Alpha Centauri, one of the two "Pointer Stars" that help stargazers find the Southern Cross in the ... More Southern Hemisphere, may have a planet in orbit around it. If it does, the Webb Telescope will find it — as long as it's Jupiter-sized. The closest star to the sun, Proxima Centauri, has a planet. It may even have two planets. Proxima Centauri is located in the constellation Centaurus, visible only from the southern hemisphere, but it's a red dwarf star too small to be seen. That brightest star in Centaurus — and the third brightest in the entire night sky — is Alpha Centauri. It's two stars (Alpha Centauri A and Alpha Centauri B) orbiting each other, with Proxima Centauri orbiting them every 550,000 years, in a weird-sounding (but not rare) three-star solar system. Does Alpha Centauri have planets around it? It's a Holy Grail among planet-hunters, mostly because Alpha Centauri is only 4.37 light-years distant. Since it's so close to the solar system, it's theoretically an ideal target for astrometry (the study of the movements of stars and celestial bodies), as well as for direct infrared imaging using the James Webb Space Telescope, two techniques that can detect planets orbiting distant stars — exoplanets. A new paper published this week in Research Notes of the American Astronomical Society details the use of the Webb telescope to study Alpha Centauri in February 2025. Although it didn't detect any planets, it provides glimpses of what may still be hiding around the star. The Alpha Centauri star system — a triple-star planetary system. According to the paper, the Webb telescope's Mid-InfraRed Instrument would have detected gas giant planets like Jupiter at about twice the Earth-sun distance from Alpha Centauri A if they were roughly similar to Earth's temperature. It's tricky because, in a system with two bright stars, light pollution is always a problem. Although the Webb telescope has a coronagraph disc to block the light from the host star (by creating an artificial eclipse) to help it detect planets in the vicinity, it doesn't have two coronagraphs to use on two separate stars. Despite that — and despite Alpha Centauri Ac being five billion years old, meaning any planets in its orbit would likely be very old, cool and therefore dim — the scientists think the Webb telescope can still be used to find large Jupiter-sized planets in its orbit. The authors call Alpha Centauri "an exceptional but challenging target for exoplanet searches." This early conclusion is based on just one set of observations from February 2025. Webb also observed Alpha Centauri A in August 2024 and April 2025, so more conclusions — and possibly a discovery of a planet — could be imminent. Illustration of the Earth-like exoplanet Proxima Centauri b orbiting the star Proxima Centauri. ... More (Illustration by Tobias Roetsch/Future Publishing via Getty Images) In 2016, astronomers found an exoplanet in Proxima Centauri's habitable zone and named it Proxima Centauri b. This exoplanet orbits its star every 11 days from just 5% of the Earth-sun distance from the star. Proxima Centauri b is thought to orbit the star's 'habitable zone,' which is defined as a distance that allows temperatures to be warm enough for liquid water to pool on the planet's surface. However, it's thought that Proxima Centauri sometimes unleashes a massive stellar flare — an energetic explosion of high energy radiation — that would make life as we know it impossible on any planets in orbit. A paper in 2020 suggested that Proxima Centauri may be orbited by a second "super-Earth" sized planet (bigger than Earth, but smaller than Uranus) about the same distance from its star as Mars is from the sun. If it exists, it orbits Proxima Centauri every 5.2 Earth years. Barnard's star is one of the fastest-moving stars in the night sky because it's just six light-years from the solar system. In October 2024, scientists unveiled a planet around it thought to be about half the size of Venus. Called Barnard's b, it's around 20 times closer than Mercury is to the sun. Wishing you clear skies and wide eyes.
