Join planetary scientist Beth Johnson as we explore a groundbreaking discovery from NASA's Curiosity rover on Mars. Scientists have identified siderite—a rare iron carbonate mineral—within ancient Martian rocks, offering new insights into Mars' once-thicker atmosphere and its now-lost carbon cycle. This discovery reshapes our understanding of the Red Planet's climate history and helps us draw powerful parallels to Earth's carbon processes. Dr. Ben Tutolo, associate professor at the University of Calgary and participating scientist on NASA's Curiosity rover team, explains that as Mars' atmosphere thinned over time, carbon dioxide was sequestered into rock formations, leading to a dramatic climate shift from a warm, wet environment to the cold, arid planet we see today. These findings provide evidence that ancient Mars was habitable and offer insights into the fragility of planetary climates. Dr. Tutolo emphasizes the parallels between Mars' atmospheric changes and current efforts on Earth to mitigate climate change by converting anthropogenic CO₂ into stable carbonates. Understanding the mechanisms of carbon sequestration on Mars could inform strategies to address climate challenges on our own planet. (Recorded live 5 June 2025.)

Why are Titan’s river deltas missing? Planetary astronomer Franck Marchis taps in for Beth Johnson to chat with Brown University’s Sam Birch and explore a strange and unexpected mystery on Saturn’s largest moon. Using data from NASA’s Cassini mission and advanced computer modeling, Birch’s team reveals that Titan's shorelines defy Earth-like expectations. Despite Titan's known rivers and seas of liquid methane, the team found a surprising absence of deltas—landforms typically formed when rivers deposit sediment at their mouths. This finding challenges existing geological expectations, as deltas are common on Earth where rivers meet larger bodies of water, and suggests that Titan's geological and climatic processes differ significantly. This discovery opens new avenues for research into Titan's sediment transport mechanisms and its potential to preserve signs of past environmental conditions or even life. (Recorded live 29 May 2025.)

What if the origin of life isn’t a one-in-a-billion cosmic fluke, but something that happens whenever the conditions are just right? Join communications specialist Beth Johnson as we explore groundbreaking research from the University of Wisconsin–Madison, where scientists have identified over 270 self-replicating chemical reactions that may have sparked life, not just on Earth, but potentially anywhere in the universe. Led by astrobiologist Dr. Betül Kaçar, this study reframes our understanding of how life can emerge from simple chemistry. Discover how these "chemical recipes" might reveal a universal pattern for life, help us search distant planets more effectively, and bring us one step closer to answering one of humanity’s biggest questions: Are we alone? (Recorded live 15 May 2025.)

A groundbreaking study from the University of Colorado Boulder suggests that ancient Mars was far from the cold, arid planet we know today. Led by Amanda Steckel, the research team utilized computer simulations to reveal that billions of years ago, Mars experienced significant precipitation—either rain or snow—that carved out extensive networks of valleys and channels across its surface. These findings challenge previous theories that Mars was predominantly cold and dry, instead supporting the idea of a warmer, wetter climate during the Noachian epoch, approximately 4.1 to 3.7 billion years ago. The study provides compelling evidence that precipitation played a crucial role in shaping the Martian landscape, offering new insights into the planet's climatic history and its potential to have supported life. Join planetary scientist Beth Johnson and Dr. Steckel as they discuss the results of this study and its implications for finding life, especially past life, on Mars. (Recorded live 8 May 2025.)

One significant threat to life here on Earth is the possibility that a massive asteroid will collide with our planet and destroy life as we know it. To understand the possibilities, large surveys of the sky have found around 95% of potentially hazardous asteroids larger than a kilometer. Smaller asteroids, however, can also cause massive amounts of damage. Estimates range from 40 to 60 percent when it comes to asteroids over 100 meters in diameter, which would be considered city-killers. Even smaller asteroids, such as the 20-meter one that exploded over Chelyabinsk in 2013, can cause destruction and injury. The more asteroids we can find, the better our predictions and future protections will be. In light of this threat, scientists have used the JWST to detect 138 of the smallest asteroids (as small as 10 meters) ever observed in the asteroid belt. These tiny asteroids are important because they can become near-Earth objects (NEOs), posing a risk to Earth through possible impacts, including powerful explosions. By analyzing the size and frequency of asteroids, researchers found a significant change in the population of asteroids around 100 meters in size, likely due to collisions breaking larger asteroids into smaller ones. The observed asteroids originated from known asteroid families and were detected using advanced tracking and infrared imaging techniques. This research enhances our understanding of asteroid behavior and may aid in predicting and mitigating future asteroid threats. Join planetary astronomer Franck Marchis in a conversation with lead authors Artem Y. Burdanov and Julien de Wit as they discuss these smaller asteroids and what they can reveal about potential threats to our planet. (Recorded live 1 May 2025.)

​A recent study proposes a new model for the evolution of intelligent life, which challenges the long-standing "hard steps" theory that the emergence of intelligent life is an exceedingly rare event due to a series of improbable evolutionary milestones. A team led by postdoctoral researcher Dan Mills from the University of Munich suggests that the development of intelligent life is a natural outcome of planetary evolution. They argue that Earth's environment underwent sequential "windows of habitability," periods when conditions became favorable for complex life to emerge. (Past Drake Award winner Jason Wright is a co-author on the study.) The study emphasizes the importance of interdisciplinary collaboration between astrophysics and geobiology to understand the evolution of life. Join planetary astronomer Franck Marchis in an in-depth discussion with Dr. Mills about why intelligent life may be common and how this could affect our search for life beyond Earth. (Recorded live 24 April 2025.)

Join Dr. Franck Marchis, Chief Science Officer and co-founder at Unistellar and director of Citizen Science at SETI Institute, and Dr. Lauren Sgro, Outreach Manager at the SETI Institute, for a conversation on citizen science with the Unistellar network in partnership with the SETI Institute. We will give an update on T CrB, share our new Satellites mode, discuss an exoplanet candidate campaign to confirm a planet, and look ahead to an occultation of asteroid 319 Leona. We will also answer your questions about our program from the Unistellar community page and discuss recent highlights. (Recorded live 17 April 2025.)

A road trip to a gypsum quarry in Algeria led Youcef Sellam on a journey of scientific discovery. From the road trip to an internship in Italy, he and his colleagues later discovered microbial fossils—marking a first for Algerian gypsum. As a Ph.D. student at the University of Bern, Sellam and his team took this research further. They used a special instrument to detect the chemical signatures of these ancient microbes, demonstrating a method that could one day help search for traces of life on Mars. Their findings, published in Frontiers in Astronomy and Space Sciences, highlight how chemical analysis can reveal biological traces in minerals. Join planetary scientist Beth Johnson and Youcef for a discussion of how this research brings us one step closer to understanding how we might detect past life on the Red Planet. (Recorded live 10 April 2025.)

In a recent study, Dr. Janice Bishop of the SETI Institute, along with postdoctoral researcher Adomas Valantinas from Brown University, propose that Mars' characteristic red hue is primarily due to ferrihydrite—a water-rich iron oxide mineral—rather than the previously assumed hematite. Analyses of data collected by Martian orbiters, rovers, and laboratory experiments showed that ferrihydrite closely matches the composition of the dust covering Mars' surface. Ferrihydrite typically forms in environments abundant in cool water, suggesting Mars once had significant liquid water on its surface. The research implies that Mars transitioned from a wet to a dry environment billions of years ago. Confirming these findings would require returning samples from Mars to Earth for comprehensive analysis. Join planetary scientist Beth Johnson for a chat with Dr. Bishop about the evidence for ferrihydrite and what it could have meant for life on Mars. (Recorded live 3 April 2025.)

In The Climate Chronicles, a podcast with 42 episodes across eight seasons, Professor Dagomar Degroot of Georgetown University "takes you on a journey through 50 million years of climate change." He delves into how climate change has shaped civilizations—from the earliest hominid ancestors to the present era of rapid global warming. Through storytelling and historical analysis, he reveals the profound influence of climate on human societies. He explains how lessons from the past can help us navigate the challenges of today and tomorrow. Join communications specialist Beth Johnson for a conversation with Professor Degroot. They will explore the intricate connections between climate, human history, and future challenges. (Recorded live 27 March 2025.)