A newsletter for unflinching, ever-curious science-lovers. ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏
October 24, 2025—This year's third Salmonella-related egg recall, disease-causing bacteria in the teeth of Napoleonic soldiers and why NASA might lose a self-declared race to return humans to the moon. —Robin Lloyd, Contributing Editor | | Astrophotographer Brennan Gilmore captured this photo of Comet Lemmon on October 4, 2025 from central Virginia. Brennan Gilmore | | - Why do some comets dazzle while others fizzle? It's a combination of how the comet is made, how and when we see it, and a bit of luck. | 5 min read
- The FDA has warned people not to eat recalled eggs contaminated with Salmonella, a bacteria that can sicken humans. Here's what to do if you have recalled eggs. | 3 min read
- Disease-causing bacteria that have been recently discovered in the teeth of Napoleonic soldiers may have spurred the massive infantry's demise during its retreat from Russia. | 3 min read
- Slow-moving tropical storm Melissa is forecast to rapidly intensify to a major hurricane and drop mind-boggling quantities of rain on Jamaica. | 3 min read
| | NASA looks unlikely to win the U.S.'s self-declared race with China to return astronauts to the moon, experts say. China is making steady progress toward its goal to place people on the moon by 2030, but the U.S. a plan to put astronauts on the moon in 2027 is unrealistic due to prior delays and testing mishaps, experts say. The sticking point is SpaceX's Starship rocket, selected as a lunar lander as part of NASA's Artemis program. The rocket has a tight timeline for demonstrating its capacity for refueling in Earth orbit and landing upright on the moon's surface. Why it matters: The stakes of this one-sided race go beyond national pride. The nation that first returns astronauts to the moon's surface could get a leg up on setting future policy for spaceflight to and colonies at the moon and Mars, reports Scientific American editor Dan Vergano. What the experts say: "I think we need to grapple with whether we care about China and the moon. We won that race. Why declare a second one?" says former NASA associate administrator for science Thomas Zurbuchen. | | Measurable associations recently have shown up between health factors and the color of one's tongue, so researchers are developing AI-based technology and an LED lighting system to standardize this diagnostic, long used in traditional Chinese medicine (TCM). The goal is to eliminate perception bias and the influences of lighting conditions in assessing tongues, reports data journalist and Scientific American intern Eve Lu. In a 2024 study, machine-learning models classified tongue colors to predict diabetes, asthma, COVID and other conditions with a testing accuracy of more than 96 percent. Why it matters: Consumers are showing interest in AI tools for tongue analysis. A recently launched AI-based wellness app called BenCao allows users to "upload tongue images and receive personalized health guidance based on TCM concepts," Lu writes. Tongue color is just one biological indicator in a complete TCM workup, so the app does not give out medical diagnoses, says University of Missouri bioinformatics researcher Dong Xu, whose team developed the wellness app. What the experts say: "I think the field [of AI-based tongue analysis] will develop by accretion of small studies that reveal correlations between tongue appearance and specific conditions. Of course, many diseases show no change in tongue appearance," says University of Buffalo oral biologist and periodontist Frank Scannapieco.
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Eve Lu; Source: "Tongue Disease Prediction Based on Machine Learning Algorithms," by Ali Raad Hassoon et al., in Technologies, Vol. 12, No. 97; June 28, 2024 | | - Do you know the answer to the first question of today's science quiz? Also, don't miss today's Spellements. If you spot any science words missing from Spellements, email them to games@sciam.com. In recent days, reader Mitch C found utile, cel and lutein, Jim G and Joaquin M found lamella and Hugh K found ala (part of the nose).
| | MOST POPULAR STORIES OF THE WEEK | | - Is There a Fundamental Limit to Human Metabolism? New Research Suggests Yes. | 3 min read
- Cells Have a Crystal Trigger That Makes Them Self-Destruct When Viruses Invade. | 3 min read
- How the World's Most Famous Code Was Cracked. | 7 min read
| | So far, clouds have kept me from stepping outdoors at night to look near the Herdsman constellation (Boötes) for Comet Lemmon, the inspiration for Scientific American contributor Phil Plait's piece above on comets that dazzle or fizzle. Fortunately, we all have another few weeks to try to catch a glimpse. This weekend, I hope you have clear night skies and a moment to gaze up and look for Lemmon. | | Please send feedback and comments about the newsletter—plus any comet-sighting reports—to: newsletters@sciam.com. —Robin Lloyd, Contributing Editor
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