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The Stars That Lit Up the Early Milky Way
Imagine trying to reconstruct the history of a city by studying only its oldest surviving buildings. You can’t watch it being built, you can’t interview the architects, all you have are the structures themselves, their materials, their arrangement, the subtle clues locked into their very fabric. That is essentially what astronomers do when they study the formation of our Galaxy, and a new study has just given them their biggest collection of clues yet.
The key lies in a type of star called an RR Lyrae variable. These ancient, pulsating stars swell and shrink over the course of just a few hours, brightening and dimming like a slow heartbeat. What makes them extraordinary is that they are almost eerily predictable. Because astronomers know precisely how bright they truly are, they can calculate exactly how far away they are just by measuring how bright they appear in the sky. They are, in the truest sense, cosmic lighthouses.
The RR Lyrae variable stars fall in a particular area on a Hertzsprung–Russell diagram of colour versus brightness (Credit : Rursus)
Crucially, RR Lyrae stars are old and we’re not talking millions of years, we’re talking more than ten billion. These stars were forming when the Milky Way itself was still taking shape, in the chaotic early universe shortly after the Big Bang. That makes them living relics, fossils of a Galaxy in the process of becoming itself.
A large international team assembled the biggest ever catalogue of these stellar fossils, thousands of them combining precise distance measurements with data from the European Space Agency’s Gaia satellite, which has mapped the positions and movements of over a billion stars with extraordinary accuracy. Together, this gave astronomers a picture of where these ancient stars are, how fast they’re moving, and in which direction, essentially, a 3D map of the early Milky Way that can be rewound like a film.
What they found challenges a long held assumption that the Milky Way’s different structural layers we see edge on in the night sky were long thought to have formed at different times. The new results suggest that they all appear to have formed remarkably quickly and at roughly the same epoch. The main difference between them isn’t age, it’s chemistry: stars in the halo contain less iron than those in the thick disk, which in turn contain less than the thin disk. Each successive layer was enriched by the deaths of previous stellar generations, a kind of celestial inheritance passed down through supernovae.
The Andromeda Galaxy is home to a number of RR Lyrae variable stars (Credit : Brody Wesner)
Perhaps the most striking finding involves our galactic neighbour, Andromeda. When the team compared the chemical fingerprints of old stars across the Milky Way with those in M31, they found strikingly similar patterns, despite the two galaxies being very different in size and having quite different histories of merging with smaller galaxies. Whatever process drove the earliest phase of galaxy formation, it seems to have operated in the same way across both.
Source : RR Lyrae Variables as Beacons to Investigate the Early Formation of the Milky Way
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AI Could Make Alien Contact More Likely for SETI’s ‘Project Hail Mary’
“Project Hail Mary,” a science-fiction novel that’s just been turned into a big-budget, big-screen movie, tells the story of an unlikely astronaut who unexpectedly encounters an alien during a desperate mission to save their respective civilizations.
The astronaut (played by Ryan Gosling in the movie) and the alien have to figure out on the spot whether they’re friends or foes. They also have to come up with a translation system that can accommodate two completely different ways of communicating.
That all makes for a do-or-die space drama reminiscent of “Apollo 13” — but the day is fast approaching when advances in astronomy and artificial intelligence could take a lot of the drama out of alien contact.
Seth Shostak, senior astronomer for the SETI Institute, says he wouldn’t be at all surprised if our first encounter with aliens came in the form of AI-to-AI contact.
“My guess is that the aliens are going to be machines, because that’s what we’re doing, right?” he says in the latest episode of the Fiction Science podcast. “We’re just in the early days of building machines that can do things that humans have had to do in the past. I’m sure that 100 years from now, the most capable intelligence on this planet will not be some sort of soft and squishy biological thing. That’s going to be a machine. And so, if we hear the aliens, I suspect that it’s more than likely that they, too, will be machines.”
If you’re worried that talking about AI and the search for aliens will require delving deeply into spoilers, never fear: Artificial intelligence doesn’t really play a role in the “Project Hail Mary” movie. It’s mentioned only once in the Andy Weir novel on which the movie is based — merely to explain why the planners of the do-or-die mission opted not to use AI. (We do get into spoilers toward the end of this post, however, so consider yourselves warned.)
For more than 65 years, astronomers have been searching the skies for radio signals that might have been sent out by extraterrestrial civilizations. “The usual approach is to build a receiver that can monitor thousands — well, today, millions of different channels simultaneously,” Shostak says. “And you can just look at how that capability has improved over time. It turns out it follows what’s called Moore’s Law … which says that the speed of electronics more or less doubles every two years.”
It takes a lot of computing power to monitor millions of channels, and Shostak says he’s certain that AI will accelerate the search for extraterrestrial intelligence, better known as SETI.
There’s already evidence of that: Last November, the Breakthrough Listen Initiative reported that an AI system developed in partnership with NVIDIA could process real-time data from telescopes searching for fast radio bursts at a rate more than 600 times faster than the current data pipeline. The system improved detection accuracy by 7% and reduced false positives by nearly an order of magnitude.
“This technology doesn’t just make us faster at finding known types of signals — it enables us to discover completely unexpected signal morphologies,” Andrew Siemion, principal investigator for the Breakthrough Listen Initiative, said in a news release. “An advanced civilization might use burst-like communications, modulated signals or transmission schemes we haven’t even imagined. This AI system can learn to recognize patterns that a human might miss entirely.”
Several years ago, another team of astronomers used a machine language algorithm to identify potential alien signals that were overlooked by other data-processing systems. (But don’t get too excited: Follow-up observations didn’t confirm that the signals came from extraterrestrial civilizations. You would have heard if they did.)
AI tools could help astronomers overcome some of the obstacles facing the SETI quest. For example, one group of researchers recently reported that signals from alien civilizations could be scrambled by stormy space weather. Improved pattern-recognition software just might be able to pick out the signal hidden in the cosmic noise.
AI models could also come into play for interpreting alien messages once they’re found. But Shostak isn’t focusing so much on that challenge. “Even if we never understand what the aliens are saying, just the fact that we pick up the signal and can tell that it’s an artificial signal — in other words, made by some technology — that’s very interesting, because we’ve proved that they’re there,” Shostak says.
Understanding what the aliens are saying “would be interesting to know, but I would consider that a secondary benefit of finding their presence,” he says.
Seth Shostak is senior astronomer at the SETI Institute. (SETI Institute Photo)
Shostak compares the challenge of deciphering alien messages to the challenge that archaeologists faced when they unearthed Egyptian hieroglyphs. “The best way to decipher the hieroglyphics is to have lots of people working on the problem, so just make them known,” he says. “I think the same sort of logic applies here.”
Douglas Vakoch, the president of METI International, has spent a lot of time working on the message translation problem. You can tell that from his organization’s acronym, which stands for “Messaging Extraterrestrial Intelligence.” He says AI can play a supporting role in detecting and decoding alien messages, but not the starring role.
“We need to realize that when we humans try to find patterns hidden in radio static, we may start out with some cut-and-dried guidelines that are very similar to the clear rules used by AI. But often we fail to realize exactly how our rules fall short, because we don’t lay them out clearly,” Vakoch told me via email. “AI forces us to get clear about how we are attempting to solve problems, and simply learning from AI how it is attempting to solve a problem can make us say, ‘You’ve missed something critical. You need to do this instead.’ ”
In his view, discovering an alien message is only half the battle.
“An even greater challenge will be understanding what it means. And that’s where humans will continue to play a role, even as AI becomes more computationally sophisticated in the years to come,” Vakoch said. “Deciphering a message from extraterrestrials will be much more ambiguous. AI might help us detect patterns in alien messages that humans would miss, but we’ll still need people to figure out what the message means.”
How long will it take to make alien contact? Will we need to wait for a do-or-die mission to a faraway star system? More than 20 years ago, Shostak predicted that we’d find evidence of aliens by 2025 or so. And for more than 15 years, he’s been betting a cup of coffee on it.
Now Shostak is acknowledging that he might have to pay up. “Next time I see you, I’ll buy you a cup of coffee,” he says. “We haven’t found them yet. … Maybe it was just wishful thinking, but honestly, I think that it was more based on the known rate of improvement in the experiments to find the aliens.”
Maybe SETI astronomers just need more time to take advantage of Moore’s Law and AI. Maybe it’ll take another 20 years, or 200 years, to follow through on the promise of “Project Hail Mary” and connect with alien travelers. But in the meantime, I’ll take that cup of coffee.
Here come the spoilers
If you haven’t already read “Project Hail Mary,” it can be tricky to keep track of the movie’s scientific twists and turns. Some of those plot twists have interesting parallels to real-world science, and I can’t resist pointing them out.
“Project Hail Mary” is scheduled for theatrical release on March 20, and it’s already getting rave reviews. For more from Seth Shostak, check out Big Picture Science, the podcast he co-hosts; and look for his columns in Astronomy magazine.
My co-host for the Fiction Science podcast is Dominica Phetteplace, an award-winning writer who is a graduate of the Clarion West Writers Workshop and lives in San Francisco. To learn more about Phetteplace, visit DominicaPhetteplace.com.
This report was originally posted on Cosmic Log, the home base for the Fiction Science podcast. Stay tuned for future episodes of Fiction Science via Apple, Spotify, Player.fm, Pocket Casts and Podchaser. Fiction Science is included in FeedSpot’s 100 Best Sci-Fi Podcasts. If you like Fiction Science, please rate the podcast and subscribe to get alerts for future episodes.
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Florida woman set to face charges for allegedly shooting at Rihanna’s home
A Florida woman is expected to be criminally charged Tuesday after she allegedly sprayed bullets at the Beverly Hills home of star singer Rihanna.
Ivana Ortiz, 35, of Orlando is expected to appear in a downtown Los Angeles courtroom on Tuesday afternoon, according to two sources with direct knowledge of the situation who spoke on the condition of anonymity in order to discuss the matter candidly because charges had yet to be officially filed.
Los Angeles police said Ortiz fired the shots from a parked car outside Rihanna’s home in the Post Office section of Beverly Hills. No one was injured, but bullets struck the singer’s home, an Airstream parked on the property and a neighbor’s house, according to one of the sources.
The singer was home at the time alongside her partner, A$AP Rocky, and their three children, according to the official. Rihanna and Rocky were in the Airstream at the time of the shooting, the official said.
“They easily could have been hit,” the official said.
Representatives for Rihanna and Rocky did not respond to a request for comment Tuesday morning.
During his weekly crime briefing Tuesday morning, Los Angeles Police Chief Jim McDonnell said a witness saw the suspect driving up and down the street outside Rihanna’s home in a white Tesla in the moments before the shooting. Officers later broadcast the vehicle’s description and a license plate reader captured the vehicle passing through Benedict Canyon, he said.
An LAPD helicopter began to track the vehicle, which was eventually pulled over in Sherman Oaks near Ventura and Sepulveda boulevards, according to McDonnell. Ortiz was arrested without incident and did not speak with detectives. Police said they found an “AR-15-style” rifle, ammunition and a blond wig in her car. Additional ammunition, including a 30-round magazine, was found in the vehicle’s trunk, the LAPD said.
A total of seven people were on the property at the time of the shooting, McDonnell said.
Ortiz is a licensed speech therapist with multiple prior arrests who had attacked Rihanna on social media in recent weeks. It was not clear who her attorney was, and attempts to contact her have been unsuccessful as she has remained in LAPD custody since Sunday.
On Feb. 17, Ortiz posted a meme to Facebook falsely alleging Rihanna had AIDS. In another post six days later, she tagged Rihanna in a post demanding the singer “say something to me directly instead of sneaking around like you talking to me where I’m not at.”
Records show Ortiz has prior arrests in Florida on charges of careless driving, domestic violence and battery. It was not clear if she was convicted of any crimes.
Police have not disclosed a motive in the attack. The case remains under investigation by the LAPD’s Robbery-Homicide Division.
L.A. County prosecutors will now find themselves on the same side of a courtroom as Rihanna and Rocky, a little over a year after the district attorney’s office tried to put the rapper in prison. Rocky — whose legal name is Rakim Meyers — faced 20 years in prison as prosecutors took him to trial on assault charges for allegedly shooting a former friend in Hollywood in 2021.
Rocky denied all wrongdoing and jumped into a courtroom gallery to hug Rihanna when he was acquitted in February 2025.
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