Zhurong Rover Spots Evidence of Recent Liquid Water on Mars ]  By Katherine Kornei , Eos/AGU.  Excerpt: Mars is hardly a verdant world today, yet evidence abounds that liquid water  once flowed over the Red Planet . Now, the latest rover to arrive on Mars’s surface—Zhurong, part of China’s  Tianwen-1 mission —has spotted hydrated minerals that point to liquid water persisting well into the Red Planet’s most recent geologic period. These results,  published in  Science Advances , contribute to our understanding of when liquid water flowed on Mars, the research team has suggested.…

Why Did Sunspots Disappear for 70 Years? Nearby Star Holds Clues By Kimberly M. S. Cartier , Eos/AGU. Excerpt: Every 11 years, the number of spots dotting the surface of the Sun increases and decreases like clockwork. Astronomers have been tracking the 11-year sunspot cycle for more than 400 years, using it to better understand the chaotic magnetic field the Sun puts out. (The current solar cycle, number 25, started in 2019.) The timing of the solar cycle is remarkably consistent: Sunspot numbers rise and fall, rise and fall…except for that time that they disappeared and weren’t seen again for 70 years. That period of time, from 1645 to 1715, is known as the  Maunder Minimum , named after 19th century British astronomers Edward and Annie Maunder. Astronomers still don’t understand why the Sun ceased making sunspots for 70 years, but a new analysis of more than 5 decades of measurements of nearby stars has identified one that might be undergoing its own Maunder-l

Astronomers may have detected a ‘dark’ free-floating black hole By Robert Sanders , UC Berkeley News.  Excerpt: If, as astronomers believe, the death of large stars leave behind black holes, there should be hundreds of millions of them scattered throughout the Milky Way galaxy. The problem is, isolated black holes are invisible. Now, a team led by University of California, Berkeley, astronomers has for the first time discovered what may be a free-floating black hole by observing the brightening of a more distant star as its light was distorted by the object’s strong gravitational field — so-called gravitational microlensing. The team, led by graduate student Casey Lam and  Jessica Lu , a UC Berkeley associate professor of astronomy, estimates that the mass of the invisible compact object is between 1.6 and 4.4 times that of the sun. Because astronomers think that the leftover remnant of a dead star must be heavier than 2.2 solar masses in order to co

Shadow of Milky Way’s giant black hole seen for the first time By Daniel Clery, Science Magazine.   Excerpt: After 5 years, astronomers release picture of Sagittarius A*’s event horizon, ringed by bright gas. Astronomers today released the first image of the supermassive black hole at the center of the Milky Way Galaxy—or at least a picture of its shadow. Eight radio observatories around the globe and more than 300 scientists joined forces to image the object known as Sagittarius A* (Sgr A*), a feat thought impossible until just a few years ago. ...The team, known as the Event Horizon Telescope (EHT), in 2019 produced the  first ever image of a black hole , at the center of the nearby giant galaxy M87. The M87 black hole is 1600 times more massive than Sgr A*. Yet the similarity of the two images—bright rings of gas trapped in death spirals around these ultimate sinkholes—shows how Albert Einstein’s theory of gravity, general relativity, works the same at all scales.… See also

Catch a failing star: the tense wait for a supernova By Robin McKie , The Guardian.  Excerpt: ...When a supernova erupts, it sprays the cosmos with heavy elements – so observing one nearby would provide precious information about the creation of matter in our galaxy. ...Scientists estimate that on average about 20 supernovae occur in a galaxy such as ours every thousand years. Yet only  five have been observed in the last millennium . East Asian and Arabic records indicate there were supernovae in 1006, 1054 and 1181, while European documents recall ones that occurred in 1572 and 1604. ...if supernovae are so brilliant, why have we only detected five in the past 1,000 years? Why have we not seen a number that is nearer the 20 suggested by observations of other galaxies? The answer is straightforward, says Sullivan. “Our galaxy is like a flat plate and our solar system is about two-thirds of the way towards its edge. A supernova that occurs

Discovery Alert: A Flood of New Planets, Plus Hint of an ‘Exomoon' By Pat Brennan, NASA's Exoplanet Exploration Program.  Excerpt: Data from NASA’s now-retired Kepler Space Telescope reveals an eclectic assortment of new planets and planetary systems that promises to deepen understanding of how exoplanets form. Some of the newly-discovered planets might make tempting targets for the James Webb Space Telescope, now being fine-tuned for its first observations this summer. The Webb telescope is expected to search for signs of atmospheres around some exoplanets, and potentially determine some of the gases and molecules present. This raft of new planets also helped push NASA’s tally of confirmed exoplanets past the 5,000 mark in March 2022. ...Combing through Kepler data also revealed another potentially significant find: a possible exomoon. ...The new possible exomoon, Kepler-1708 b-i, would be very large for a moon, about 2.6 times as big around as E

Giant Planet’s Formation Caught in Action By Jure Japelj , Eos/AGU.  Excerpt: Astronomers took a direct image of a massive protoplanet embedded in a protoplanetary disk. The system provides strong evidence for an as-yet-unconfirmed theory of planet formation. ...Jupiter-class gas giants on far-flung orbits have challenged what is known as the standard formation scenario. Scientists  converged  on the scenario that our solar system’s giant planets formed via accretion within the gaseous protoplanetary disk. Rocky planetary cores fed on pebbles or planetesimals, and once the cores reached a certain mass, they began gobbling up the surrounding gas, rapidly becoming giant planets. But that process works only when planets form relatively close to their host stars—the gas giants found on wide orbits would not have had time to grow a sufficiently massive core before the gaseous disk dissipated. The unstable disk model is one of several alternative models  suggesting