Summer Meteor Showers, Short Summer Days and Ancient Arthropods

Scientific American

a day ago

Rachel Feltman: Happy Monday, listeners! For Scientific American 's Science Quickly, I'm Rachel Feltman. It's been a while, but we're finally back with our usual science news roundup. Let's catch up on some of the science news you might have missed in the last week or so.
If last Tuesday seemed to fly right by, that's probably because it was a little shorter than usual. The International Earth Rotation and Reference Systems Service says that July 22 was around .8 milliseconds short of the standard 24 hours. That's slightly less dramatic than the almost 1.4 milliseconds that were missing from July 10, and scientists anticipate another ever-so-slightly truncated day on August 5.
Now, while there were plenty of headlines about these missing fractions of a milliseconds, it's not actually news that the Earth's rotation varies in speed. The length of a single rotation—also known as a day—is impacted by factors such as the movements of our planet's liquid core, variations in the jet stream and the gravitational pull of the moon. One 2024 study even suggested that melting polar ice has decreased Earth's angular velocity enough to slow rotations down.
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In fact, earth's days have generally been trending longer if you look back at the last few billion years. Research suggests that at various points in the time before our species evolved, days were minutes and even hours shorter. But we always get our shortest days in the summer, and there have been some especially short ones over the last few years. Scientists aren't totally sure why that's been happening, but they expect the spike to flatten back down soon, according to reporting by The Guardian.
Speaking of the movement of celestial heavenly bodies: two meteor showers are set to peak on the same evening this week. In the overnight from July 29 to 30 both the Southern delta Aquariids and the alpha Capricornids will be reaching the height of their activity. While the alpha Caricornids aren't known for dropping loads of visible objects, they do sometimes produce bright fireballs—plus they can be seen from anywhere on the planet.
Meanwhile, folks in the Southern Hemisphere will also get a great view of the Southern delta Aquariids, and people farther north could catch some activity if they look southward. There will also be some scattered meteors from the Perseids, which will ramp up in activity next month. With the moon in a waxing crescent phase, conditions should be good for spotting meteors—as long as it's not too cloudy. So set an alarm for the predawn hours on Wednesday and go outside to take a peek.
Now let's head back down to Earth. Last Monday the Federal Emergency Management Agency's Urban Search and Rescue chief resigned. Ken Pagurek, who spent more than a decade with the FEMA branch and served as its chief for about a year, reportedly told colleagues that his decision was motivated in part by the delayed response to Texas's recent catastrophic flooding. The Department of Homeland Security recently implemented a policy that requires Secretary Kristi Noem to personally approve any spending over $100,000. CNN reports that Noem took more than 72 hours to provide authorization for Urban Search and Rescue teams to deploy in Texas. According to the New York Times, Noem also failed to renew agreements with call center companies whose contractors would have answered calls from disaster survivors. The contracts lapsed in the aftermath of the flood, when many people were still in need of help. The Times reported on July 5, FEMA received a bit more than 3,000 calls and answered about 99.7 percent of them. On July 6, with hundreds of the contractors responsible for answering phones suddenly fired, FEMA reportedly received 2,363 calls and answered about 35.8 percent of them. And according to the Times, those contracts weren't renewed until July 10.
When asked for comment on Pagurek's resignation by ABC News, a DHS spokesperson doubled down on the new spending policy, defending the agency's decision not to 'hastily approve a six-figure deployment contract without basic financial oversight.'
Let's pivot to some health news. According to a study of nearly 1,000 people published last Tuesday in the journal Nature Communications, the COVID pandemic may have made our brains age more quickly—regardless of whether we got sick.
First, the researchers analyzed imaging from more than 15,000 healthy individuals collected pre-pandemic to establish a baseline for normal brain aging. The team used this data to train machine-learning models to predict a person's brain age based on certain structural changes. The researchers then applied those models to brain scans from 996 other subjects, all of whom had received two brain scans at least a couple of years apart. About half of the participants had received both scans prior to the start of the pandemic, so they served as the control group.
The scientists were then able to look at scans taken before and after the pandemic to assess the rate of brain aging. While only folks who got infected with COVID between their two scans showed a dip in some cognitive abilities, signs of brain aging, such as the shrinkage of gray matter, were accelerated across the board. The effects were most pronounced among men, older individuals and people from more socioeconomically deprived backgrounds.
The study authors pointed to a number of aspects of the pandemic—including increases in stress, alcohol consumption and economic insecurity, along with decreases in physical activity and socialization—that they believe may have made our brains age more quickly. We don't yet know what the implications of these changes might be or whether they're reversible.
Speaking of brains—and to end our show on a fun story because you know I love to do that—let's talk about ancient sea critters. A recent study focused on the extinct species Mollisonia symmetrica, which lived around half a billion years ago, suggests that the ancestors of spiders and other arachnids may have started out in the ocean. In studying fossilized remains of the tiny creature, scientists found that its brain was basically backwards—at least compared to other arthropods. The layout is more similar to the way modern arachnid noggins are arranged, which suggests that spider brains may have first evolved in the sea.
That's all for this week's news roundup. We'll be back on Wednesday to talk about some of this summer's hottest topics in the world of weather.
Science Quickly is produced by me, Rachel Feltman, along with Fonda Mwangi, Kelso Harper and Jeff DelViscio. Shayna Posses and Aaron Shattuck fact-check our show. Our theme music was composed by Dominic Smith. Subscribe to Scientific American for more up-to-date and in-depth science news.