Latest news with #AnnaGülcher
Yahoo
20-05-2025
- Science
- Yahoo
Curious circles on Venus suggest its surface is still changing
When you buy through links on our articles, Future and its syndication partners may earn a commission. A new study reveals overlooked signs of geological activity on Venus — clues that the planet's mysterious surface is still changing today. These signs, found in giant circular features called "coronae," may not only reshape our understanding of Venus, but also offer a glimpse into Earth's own ancient past. Coronae are vast, oval-shaped structures ranging in size from dozens to hundreds of miles wide. They are believed to form when hot, plumes from deep inside a planet push against its outer shell called the lithosphere. Imagine a slow-motion bubble of molten rock pressing upward beneath the surface, warping and cracking the crust above. These dramatic geological features, encircled by rings of fractures, are scattered across Venus, offering a stunning window into the planet's inner workings, scientists say. "They are very large features, and people have proposed different theories over the years as to how they formed," said coauthor Anna Gülcher, a planetary scientist at the University of Bern in Switzerland, in a NASA/JPL statement. "The most exciting thing for our study is that we can now say there are most likely various and ongoing active processes driving their formation." These massive ovals once dotted our planet's landscape, so studying them on Venus can reveal much about both planets, scientists say. "Coronae are not found on Earth today; however, they may have existed when our planet was young and before plate tectonics had been established," said the study's lead author, Gael Cascioli, assistant research scientist at the University of Maryland, Baltimore County, and NASA's Goddard Space Flight Center in Greenbelt, Maryland in the statement. "By combining gravity and topography data, this research has provided a new and important insight into the possible subsurface processes currently shaping the surface of Venus." To figure out the most likely process behind the formation of coronae on Venus, the team built a 3D computer model that simulates the flow of hot material inside the planet — like a virtual experiment of the planet's inner workings. They tested different formation scenarios and compared their results with gravity and topography data collected by NASA's Magellan spacecraft, which mapped Venus in the early 1990s. The gravity data, which measured the strength of gravity at different points along the planet's surface, turned out to be a game-changer. This is because denser material pulls more strongly on nearby objects, while less dense material exerts a weaker pull. The data helped the scientists detect hidden plumes of hot, less dense material rising from deep inside Venus, something that surface maps alone couldn't reveal. Out of 75 coronae examined, 52 showed signs of these underground forces still at work, hinting that tectonic activity may be more widespread on Venus than previously thought. The team believes that several tectonic processes may be shaping Venus's surface around the coronae. In some cases, subduction-like activity — a process where one part of a planet's outer shell is forced downward into the hotter, deeper interior — occurs as hot plumes rise and push surface material outward and downward. This is similar to how tectonic plates interact on Earth. They also say that another process called lithospheric dripping, which involves cooler, heavier parts of the surface sinking into the hotter mantle below, could be responsible for the tectonic activity underlying the coronae. A third possibility is that plumes beneath thicker crust trigger volcanic activity above. RELATED STORIES: — Venus facts: Everything you need to know about the 2nd planet from the sun — How 'Earth's twin' Venus lost its water and became a hellish planet — Mysteries of Crown-like Structures on Venus' Surface Unveiled in New Study Whatever the cause of the coronae might be, they suggest that Venus may be geologically active in complex and varied ways, giving researchers insight into how tectonics might work on planets without Earth-like plate boundaries — and possibly how Earth looked in its earlier, more dynamic past. While a significant and extensive study, the team relied on old data, and higher resolution images captured by the upcoming VERITAS mission will help them clarify their results. "The VERITAS gravity maps of Venus will boost the resolution by at least a factor of two to four, depending on location — a level of detail that could revolutionize our understanding of Venus' geology and implications for early Earth," said study coauthor Suzanne Smrekar, a planetary scientist at JPL and principal investigator for VERITAS, in JPL's statement. VERITAS is set to launch in 2031. A study of coronae on Venus was published in the journal Science Advances.
Scientific American
14-05-2025
- Science
- Scientific American
Venus Isn't (Geologically) Dead
Earth's geology is downright vital. Here, giant 'plates' of the crust rift apart and smash together like pieces of an ever changing planetary jigsaw puzzle. Mountains rise, volcanoes spew, and Earth itself quakes as the crust constantly remakes itself in the ceaseless cycle of plate tectonics. This is a process that controls the flow of carbon through our planet and stabilizes its climate; were it not for plate tectonics, Earth might not be habitable at all. No other rocky world in our solar system has anything approaching Earth's degree of geological activity. At least, that's what scientists used to think. Mercury, Mars and the moon appear essentially inert. But Venus, our closest neighbor and the only other large rocky world around the sun, is now starting to look far livelier than once thought. A fresh look at decades-old data from NASA's Magellan probe has found evidence of active tectonics—around dozens of circular volcanic features called coronae—on Venus today. The finding, published on Wednesday in Science Advances, provides some of the best evidence to date that Venus isn't dead—at least, not when it comes to tectonics. 'Venus works differently than the Earth but not as different as what was originally assumed,' says the study's co-lead author Anna Gülcher of the University of Bern in Switzerland. 'We should think of tectonics as not just a black-and-white picture.' On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. 'Questions as fundamental as 'Is Venus alive today?' are extremely hard to answer,' says planetary scientist Paul Byrne of the University of Washington in St. Louis, who wasn't involved in the study. This new evidence of geological activity around the coronae suggests 'the heart of Venus still beats today. I think that's extremely invaluable for us to understand the big, rocky world next door.' Venus is called ' Earth's evil twin ' for good reason: the planet is almost exactly as large as the Earth and is made of roughly the same stuff. But while Earth is a verdant water world, Venus is a scorched hellscape with temperatures hot enough to melt lead, a dreary, permanently overcast sky and air so thick that it crushes spacecraft as if they were tin cans. For a while, Venus was widely assumed to be just as dead on the inside as it is on the outside. Lacking any obvious plate tectonics—which can help release a world's internal heat—Venus's interior was thought to instead just simmer like the contents of a tight-lidded pot on a stove. According to one popular hypothesis, the pot had eventually boiled over: after eons of frustrated heating, some 800 million years ago, the planet's outer shell buckled, and Venus's entire surface was paved over with immense outpourings of fresh lava. And, the thinking went, with all that heat dissipated, the planet's geology basically shut down. But evidence is mounting that Venus is, geologically at least, still kicking. Most notably, in 2023 two researchers scrutinizing 30-year-old Magellan data realized that the probe had caught a volcanic eruption in the act: radar images of the volcano Maat Mons that were taken months apart showed what looked like a caldera collapse and subsequent lava flow. Venus, it seems, still has active volcanoes. Some researchers now think it could have active tectonics, too. And in 2020 Gülcher and her colleagues showed via simulations of Venusian tectonics that the planet's mysterious, ring-shaped coronae could be a good place to look for such activity. Tectonics refers to the processes that deform a rocky planet's brittle outer shell. On Earth, this outer shell—the lithosphere, which includes the crust and part of the upper mantle—is broken into tectonic plates that drift over the hot, plastic mantle. When two plates collide, one of them can slide below the other and dive down into the mantle in a process called subduction. On Earth, subducting plates start melting as they sink, feeding volcanoes along plate boundaries. Such volcanoes include Japan's Mount Fuji and western North America's Cascade Range. Unlike Earth, Venus doesn't have global plate tectonics. The new study suggests, however, that around coronae, something quite similar to subduction could be happening. Gülcher and her colleagues simulated several tectonic processes that might be occurring around coronae and compared their predictions to real observations collected by the Magellan probe 30 years ago. The comparisons were more than skin-deep: the researchers used gravity data to take a peek underground. Hot rock is generally less dense than cold rock, and these density variations from place to place can correspondingly alter the strength of a planet's gravitational field. So Magellan's spatial mapping of Venus's gravity can 'see' if there's hot, light material under a corona—a sign that rock is actively rising up from the mantle below. Of the 75 coronae that the team could resolve in Magellan's gravitational maps, 52 seem to be geologically active. The predicted and real data lined up so well for some coronae that 'we could hardly believe our eyes,' says the study's other co-lead author Gael Cascioli of NASA's Goddard Space Flight Center and the University of Maryland, Baltimore County. Most of the active coronae were encircled by trenches, a hint that old crust dives into Venus's mantle around these rocky rings, where it is driven downward as buoyant rock rises from below in the middle of each corona's ring structure. 'Basically, if something goes down, something goes up,' Gülcher says. Where the lithosphere is softer and more pliable, bits of it could break off and 'drip' down into the mantle in globs. In places where the lithosphere is stiffer, entire slabs of crust could subduct in a small-scale, circular mirror of Earth's subduction zones, like those that form the Pacific Ocean's famed volcanic Ring of Fire. Working with 30-year-old data comes with an obvious limitation: the data quality often isn't very good compared with newer observations. The new study's researchers did well with what they had, Byrne says. But NASA's upcoming VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) mission could do much better—and the team predicted exactly how much better in the paper. 'The improvement would be extraordinary,' Cascioli says. Instead of being limited to analyzing 75 coronae, VERITAS's gravity dataset should allow scientists to examine hundreds of the strange ring-shaped features. For the foreseeable future, Venus is the only other large, rocky world that we or our robotic emissaries will ever reach. Understanding why Earth and Venus ended up so different despite having so much in common helps us understand our own planet—and whether the rocky worlds we're beginning to glimpse around other stars are more like Earth or instead resemble its evil twin. 'Venus is the world that we probably understand least,' Byrne says. 'Yet it's the one, arguably, I think, that's the most important.'
