What Happened to Neptune's Moons?

New JWST observations suggest that some of Neptune's small inner moons may be remnants of much larger icy worlds destroyed billions of years ago. Using JWST, researchers studied Neptune's rings and three of its inner moons — Larissa, Galatea, and Proteus — and discovered compositions unlike anything previously seen in the outer solar system. Larissa, Galatea, and the rings contain magnesium-rich clay minerals that form in the presence of liquid water, yet show no evidence of the water ice scientists expected. Where did those minerals come from? One possibility points to a dramatic event in Neptune's past: the capture of Triton. Neptune's largest moon likely formed elsewhere before being captured into its unusual retrograde orbit. That gravitational upheaval may have destroyed an earlier system of large icy moons, exposing material from deep within their interiors. Some of the debris could then have reassembled into the small moons and rings we see today. Join SETI Live host Dr. Moiya McTier and lead author Dr. M. Ryleigh Davis of UC San Diego as they explore what JWST has revealed about Neptune's strange moon system, Triton's potentially destructive arrival, and how the remains of ancient worlds could offer a rare glimpse inside the icy bodies of the outer solar system. Read more: https://www.caltech.edu/about/news/neptunes-inner-moons-may-be-shattered-remains-of-ancient-icy-worlds  Read the paper: https://www.science.org/doi/10.1126/sciadv.aeb1437 

Astronomers may have found the first convincing evidence of a moon-like object beyond our Solar System — but calling it a "moon" turns out to be surprisingly complicated. Using the CRIRES+ instrument on ESO's Very Large Telescope, researchers detected evidence of a massive object orbiting a brown dwarf in the young CD-35 2722 system. The newly detected object is at least as massive as Jupiter, while its brown-dwarf companion is more than 30 times Jupiter's mass. That brown dwarf, in turn, orbits a star. So what exactly have astronomers discovered: a moon, a planet, an exosatellite — or something that shows our familiar astronomical labels aren't quite ready for the diversity of other planetary systems? Join SETI Institute senior planetary astronomer Dr. Franck Marchis and lead author Kevin Hoy as they explore how astronomers detected this unusual object, why previous exomoon candidates have been so difficult to confirm, and what this strange system could teach us about how planets, moons, and brown dwarfs form. Press release: https://www.eso.org/public/news/eso2610/  Paper: https://www.nature.com/articles/s41586-026-10751-w 

Why do some solar eruptions blast into space while others never make it? SETI Institute heliophysicist Dr. Becca Robinson talks with Dr. Kathy Reeves of the Center for Astrophysics | Harvard & Smithsonian about new research revealing what can stop a solar eruption in its tracks. Using observations of a failed solar eruption in March 2024, Reeves and her colleagues examined how the Sun's complex magnetic fields can both drive an eruption upward and ultimately prevent it from escaping. Their research shows how magnetic reconnection above an eruption can weaken it, while strong overlying magnetic fields act as a kind of cage, trapping the material before it can develop into a coronal mass ejection. Understanding why some solar eruptions succeed while others fail could improve our understanding of space weather—and may even help explain why astronomers see powerful flares on other stars but relatively few stellar coronal mass ejections. What determines whether an eruption escapes? What can this event teach us about the Sun's magnetic environment? And what could it tell us about space weather around other stars and planets? Press release: https://www.cfa.harvard.edu/news/astronomers-uncover-why-some-solar-eruptions-die  Paper: https://www.nature.com/articles/s41550-026-02872-z 

One of the coldest planetary-mass objects ever directly imaged has been hiding something unusual in its atmosphere: salt clouds. Known as the "Pink Planet," GJ 504 b is a mysterious world orbiting a Sun-like star about 57 light-years from Earth. At roughly 25 times Jupiter's mass, it lies near the uncertain boundary between giant planets and brown dwarfs. It is also so cold and faint that previous attempts to study its atmosphere from the ground were unsuccessful. Now, JWST has captured the first direct spectrum of GJ 504 b. The observations revealed an atmosphere containing water vapor, methane, carbon dioxide, ammonia, hydrogen sulfide, and other molecules. When researchers modeled the spectrum, they found that clouds—particularly salt clouds—were essential to explaining what JWST observed. Join host Dr. Moiya McTier and lead author Dr. Aneesh Baburaj (Northwestern University) to learn how astronomers separated the faint light of GJ 504 b from the glare of its host star, what salt clouds can tell us about cold planetary atmospheres, and why scientists still are not sure whether the Pink Planet formed like a planet or a star. Read the paper: https://iopscience.iop.org/article/10.3847/1538-3881/ae6919  Read the Northwestern University story: https://news.northwestern.edu/stories/2026/06/famous-pink-planet-harbors-a-salty-surprise 

NASA's next great observatory is here. The Nancy Grace Roman Space Telescope is designed to revolutionize our understanding of the universe, from dark energy to thousands of newly discovered exoplanets. But one of its most exciting instruments is the Coronagraph—a cutting-edge technology that can block the overwhelming glare of distant stars, allowing astronomers to directly observe planets orbiting them. Joining host Dr. Franck Marchis is Dr. Margaret Turnbull, senior scientist at the SETI Institute and Co-Principal Investigator on Roman's Coronagraph Instrument. She'll explain how this remarkable technology works, what we'll learn from the mission, and why Roman is paving the way toward future telescopes capable of imaging Earth-like worlds. We'll discuss: • Why Roman is NASA's newest flagship space observatory • How a coronagraph "creates an artificial eclipse" • The challenge of directly imaging exoplanets • What Roman will reveal about giant planets and planetary systems • How Roman prepares us to search for potentially habitable worlds • What excites scientists most as launch approaches Whether you're fascinated by exoplanets, space telescopes, or the search for life beyond Earth, this episode offers a behind-the-scenes look at one of NASA's most ambitious missions.

Fifty years ago, on July 20, 1976, Viking 1 became the first spacecraft to successfully land and operate on Mars, transforming our understanding of the Red Planet and launching a new era of planetary exploration. Today, sophisticated robotic explorers like Curiosity and Perseverance continue that legacy, searching for signs of ancient habitability and preparing the way for future human missions. Join host Dr. Simon Steel and planetary scientist Dr. Pascal Lee as they explore the remarkable history of Mars rovers and landers—from Viking, Sojourner, Spirit, Opportunity, Curiosity, and Perseverance to the next generation of robotic explorers being developed for Mars, the Moon, and beyond. They'll discuss what we've learned from five decades of exploration, the technologies that made it possible, and where robotic exploration may take us next. Recent concepts even include adapting Mars rover technology for future lunar missions. What have Mars rovers taught us about our neighboring world? What mysteries remain unsolved? And what might the next 50 years of planetary exploration look like?

Are we searching for extraterrestrial intelligence the wrong way? For decades, SETI researchers have focused on finding narrowband radio signals that might stand out from the natural universe. But what if an advanced civilization that wanted to communicate chose a very different strategy? Join host Dr. Lauren Sgro and UCLA astronomer Dr. Ben Zuckerman as they discuss his new paper, Broadband Searches for Extraterrestrial Technological Intelligence: A New Strategy to Find Nearby Alien Civilizations. The research proposes a new approach to SETI that focuses on broadband signals and existing astronomical surveys, potentially changing how we search for evidence of technological civilizations beyond Earth. Could signs of extraterrestrial technology already be hidden in data we've collected for entirely different purposes? What can current observations tell us about the likelihood of nearby communicative civilizations? And what does the cosmos's apparent silence really mean? Paper: https://iopscience.iop.org/article/10.3847/1538-4357/ae4c38 

Could hazy exoplanet atmospheres be hiding important clues about alien worlds? Many potentially habitable planets orbit small, active stars that frequently unleash powerful bursts of ultraviolet radiation. New research shows that this radiation can alter the chemistry and optical properties of atmospheric hazes, changing what astronomers see when they observe these distant worlds. Join host Dr. Moiya McTier as she welcomes graduate researcher Lori Huseby (University of Arizona) and Dr. Sarah Moran (NASA Goddard Space Flight Center) to discuss how laboratory experiments are helping scientists understand how stellar radiation affects water-rich exoplanet atmospheres. Their findings could improve how we interpret James Webb Space Telescope observations and future missions searching for signs of habitability beyond our Solar System. How do stellar flares reshape alien skies? What do atmospheric hazes tell us about a planet's environment? And could understanding these hazes help us identify worlds capable of supporting life? Paper: https://iopscience.iop.org/article/10.3847/1538-4357/ae6cdb 

The James Webb Space Telescope is transforming our understanding of exoplanets—but what happens when clouds get in the way? Astronomers have developed a new method to detect clouds and hazes in distant planetary atmospheres, helping researchers determine when they're seeing the planet itself and when weather obscures the view. Join SETI Live as host Dr. Lauren Sgro welcomes lead author Dr. Sagnick Mukherjee to discuss this innovative method, how it works, and what it means for the future of exoplanet science and the search for life beyond Earth. Press release: https://hub.jhu.edu/2026/05/21/astronomy-exoplanet-atmospheres-detecting-clouds/  Paper: http://www.science.org/doi/10.1126/science.adx5903 

What happens after we discover evidence of extraterrestrial intelligence? The International Academy of Astronautics has just ratified the first major update to the SETI post-detection protocols in more than 15 years. These new guidelines address the realities of today's world, including social media, AI-generated misinformation, deepfakes, international coordination, and the challenge of responsibly communicating extraordinary discoveries. At the same time, the SETI Institute has launched the Discovery and Futures Lab, a new interdisciplinary initiative dedicated to exploring the scientific, social, ethical, legal, and cultural implications of discovering life beyond Earth. Join host Dr. Lauren Sgro and guests Dr. Lucian Walkowicz and Dr. Chelsea Haramia as they discuss what these new protocols mean, why humanity needs to prepare for transformative discoveries before they happen, and how scientists, policymakers, communicators, and the public might respond if we ever receive convincing evidence that we are not alone. Could humanity agree on how to respond? How do we combat misinformation? Who gets to speak for Earth? And what can history teach us about one of the biggest discoveries in human history? Tune in for a fascinating conversation about the future of discovery, responsibility, and our place in the cosmos. Press release on the updated protocols: https://www.seti.org/news/beyond-disclosure-day/  Press release on the Discovery and Futures Lab: https://www.seti.org/news/seti-institute-launches-discovery-and-futures-lab-to-explore-the-human-dimensions-of-life-beyond-earth/