The ring would have gradually fallen to Earth as meteorites, correlating to a spike of impacts seen in the geological record. Also, a new AI tool can judge whether sand came from a beach, a river, a glacial deposit, or a wind-blown dune.

Hundreds of millions of years ago, Earth may have looked quite different when viewed from space: Scientists propose it may have had a Saturn-like ring, made up of lots of smaller asteroids.

The new paper, published in Earth and Planetary Science Letters, proposes that this ring formed around 466 million years ago. A major source of evidence is a band of impact craters near the equator. The researchers also posit the ring would have shaded this equatorial area, possibly changing global temperatures and creating an icehouse period.

Ira speaks to Rachel Feltman, host of the Popular Science podcast “The Weirdest Thing I Learned This Week,” about this and other top science stories of the week, including how lizards use bubbles to “scuba dive” underwater, and ancient cave art that possibly shows a long-extinct species.

If you were given a bucket of sand and asked to determine where it came from, you’d probably have a hard time guessing if it was from a beach, a riverbank, the playground down the street, or a Saharan sand dune.

There are experts who can make a guess at that sort of ID, using a categorization process that takes skill, a scanning electron microscope, and hours of time. Now, however, researchers report in the Proceedings of the National Academy of Sciences that they’ve developed an AI model that can quickly judge whether a sample of sand came from a beach, a river, a glacial deposit, or a wind-blown dune.

That type of identification isn’t just of interest to geologists. Sand is one of the world’s most in-demand resources, second only to water in use. And different applications need different types of sand—for instance, making concrete and mortar requires angular sand for good adhesion and stability. These kinds of needs have given rise to illicit sand mining, sand theft, and sand smuggling. A way of rapidly identifying the origins of a sample of sand could be useful to investigators, or to companies seeking to ensure sustainability goals.

Michael Hasson, a PhD candidate in Stanford’s Department of Earth and Planetary Sciences, joins SciFri’s Charles Bergquist to discuss the new SandAI, and the challenges of tracking grains of sand.

Transcripts for each segment will be available after the show airs on sciencefriday.com.

Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.