Get ready for a journey across the rivers of our Solar System in this week's Planetary Radio. Sam Birch, an assistant professor at Brown University, explores what we know about the alluvial rivers of Earth, Mars, and Saturn’s moon Titan. Stay tuned for the What's Up segment with Bruce Betts and the last question in our on-air space trivia contest.

Discover more at: https://www.planetary.org/planetary-radio/2023-rivers-of-earth-mars-and-titan

Get ready for a journey across the rivers of our Solar System in this week's Planetary Radio. Sam Birch, an assistant professor at Brown University, explores what we know about the alluvial rivers of Earth, Mars, and Saturn’s moon Titan. Stay tuned for the What's Up segment with Bruce Betts and the last question in our on-air space trivia contest.
Discover more at: <a href="https://www.planetary.org/planetary-radio/2023-rivers-or-Earth-Mars-and-Titan">https://www.planetary.org/planetary-radio/2023-rivers-of-earth-mars-and-titan</a>

Planetary Radio brings you the human adventure across our Solar System and beyond. We visit each week with the scientists, engineers, leaders, advocates, and astronauts who are taking us across the final frontier. Regular features raise your space IQ while they put a smile on your face. Join host Sarah Al-Ahmed and Planetary Society colleagues including Bill Nye the Science Guy and Bruce Betts as they dive deep into space science and exploration. The monthly Space Policy Edition takes you inside the DC beltway where the future of the US space program hangs in the balance. Visit planetary.org/radio for an episode guide and much more.

Planetary Radio brings you the human adventure across our Solar System and beyond. We visit each week with the scientists, engineers, leaders, advocates, and astronauts who are taking us across the final frontier. Regular features raise your space IQ while they put a smile on your face. Join host Sarah Al-Ahmed and Planetary Society colleagues including Bill Nye the Science Guy and Bruce Betts as they dive deep into space science and exploration. The monthly Space Policy Edition takes you inside the DC beltway where the future of the US space program hangs in the balance. Visit planetary.org/radio for an episode guide and much more.

Planetary Radio: Space Exploration, Astronomy and Science

Planetary Radio brings you the human adventure across our solar system and beyond. We visit each week with the scientists, engineers, leaders, advocates, and astronauts taking us across the final frontier. Regular features raise your space IQ while they put a smile on your face. Join host Sarah Al-Ahmed and Planetary Society colleagues including Bill Nye, the Science Guy, and Bruce Betts, chief scientist for The Planetary Society, as they dive deep into the latest space news. The monthly Space Policy Edition takes you inside the DC beltway with Casey Dreier and Jack Kiraly to discuss the politics of space exploration in the US and advocacy actions you can take to support the missions that matter. Visit planetary.org/radio for the space trivia contest, an episode guide, and much more.

Planetary Radio brings you the human adventure across our solar system and beyond. We visit each week with the scientists, engineers, leaders, advocates, and astronauts taking us across the final frontier. Regular features raise your space IQ while they put a smile on your face. Join host Sarah Al-Ahmed and Planetary Society colleagues including Bill Nye, the Science Guy, and Bruce Betts, chief scientist for The Planetary Society, as they dive deep into the latest space news. The monthly Space Policy Edition takes you inside the DC beltway with Casey Dreier and Jack Kiraly to discuss the politics of space exploration in the US and advocacy actions you can take to support the missions that matter. Visit planetary.org/radio for the space trivia contest, an episode guide, and much more.

Sam Birch, an assistant professor at Brown University, explores what we know about the alluvial rivers of Earth, Mars, and Saturn's moon Titan.

Comparing the rivers of Earth, Mars, and Titan

Famed astrophysicist and science communicator Adam Frank shares his sense of wonder and humor in a live conversation about his excellent new book, “The Little Book of Aliens.” Join Adam and host Mat Kaplan as they explore the origin of life, the search for extraterrestrial intelligence, and whether all those UFO sightings are worthy of deeper investigation.

Discover more at: https://www.planetary.org/planetary-radio/book-club-adam-frank

Famed astrophysicist and science communicator Adam Frank shares his sense of wonder and humor in a live conversation about his excellent new book, &ldquo;The Little Book of Aliens.&rdquo; Join Adam and host Mat Kaplan as they explore the origin of life, the search for extraterrestrial intelligence, and whether all those UFO sightings are worthy of deeper investigation.
Discover more at:&nbsp;<a href="https://www.planetary.org/planetary-radio/book-club-adam-frank">https://www.planetary.org/planetary-radio/book-club-adam-frank</a>

The delightful astrophysicist and science communicator Adam Frank shares his thoughts about the search for life and intelligence across the Universe in the Planetary Society’s member book club.

Book Club Edition: The Little Book of Aliens by Adam Frank

Our Solar System is wrapped in a vast, invisible bubble created by the Sun, a protective region that shields Earth and the planets from much of the radiation that fills our galaxy. But until recently, scientists have only had rough sketches of what this boundary looks like and how it behaves.

In this episode of Planetary Radio, host Sarah Al-Ahmed is joined by David McComas, professor of astrophysical sciences at Princeton University and principal investigator of NASA’s Interstellar Mapping and Acceleration Probe (IMAP) and Interstellar Boundary Explorer (IBEX) missions, along with Matina Gkioulidou, a heliophysicist at Johns Hopkins Applied Physics Laboratory, former IMAP-Ultra instrument lead, and current IMAP project scientist and co-investigator.

Now stationed at the Sun–Earth L1 Lagrange point, IMAP uses 10 instruments to study the heliosphere — the region where the solar wind collides with material from interstellar space. The mission does this by tracking energetic neutral atoms, particles that travel in straight lines from distant regions of the heliosphere, allowing scientists to map areas of space that spacecraft can’t directly sample.

McComas and Gkioulidou explain how IMAP builds on the legacy of Interstellar Boundary Explorer, what makes this mission different, and why understanding the Sun’s influence across space matters not just for fundamental science, but for space-weather forecasting and protecting technology and astronauts closer to home.

Discover more at: https://www.planetary.org/planetary-radio/2026-imap

Our Solar System is wrapped in a vast, invisible bubble created by the Sun, a protective region that shields Earth and the planets from much of the radiation that fills our galaxy. But until recently, scientists have only had rough sketches of what this boundary looks like and how it behaves.
In this episode of Planetary Radio, host Sarah Al-Ahmed is joined by David McComas, professor of astrophysical sciences at Princeton University and principal investigator of NASA&rsquo;s Interstellar Mapping and Acceleration Probe (IMAP) and Interstellar Boundary Explorer (IBEX) missions, along with Matina Gkioulidou, a heliophysicist at Johns Hopkins Applied Physics Laboratory, former IMAP-Ultra instrument lead, and current IMAP project scientist and co-investigator.
Now stationed at the Sun&ndash;Earth L1 Lagrange point, IMAP uses 10 instruments to study the heliosphere &mdash; the region where the solar wind collides with material from interstellar space. The mission does this by tracking energetic neutral atoms, particles that travel in straight lines from distant regions of the heliosphere, allowing scientists to map areas of space that spacecraft can&rsquo;t directly sample.
McComas and Gkioulidou explain how IMAP builds on the legacy of Interstellar Boundary Explorer, what makes this mission different, and why understanding the Sun&rsquo;s influence across space matters not just for fundamental science, but for space-weather forecasting and protecting technology and astronauts closer to home.
Discover more at:&nbsp;<a href="https://www.planetary.org/planetary-radio/2026-imap">https://www.planetary.org/planetary-radio/2026-imap</a>

Host Sarah Al-Ahmed speaks with David McComas, principal investigator of IMAP and IBEX, and Matina Gkioulidou, IMAP project scientist, about how energetic neutral atoms let us map the heliosphere.

IMAP and the shape of the heliosphere

What does it really mean to enter interstellar space, and what have we learned since humanity first crossed the invisible boundary between our Sun and the stars?

In this episode of Planetary Radio, we explore the science of the heliosphere and the realm beyond with Linda Spilker, project scientist for the Voyager mission at NASA Jet Propulsion Laboratory. Drawing on decades of experience with the twin spacecraft, Spilker shares how Voyager reshaped our view of the Solar System’s outer frontier, from the nature of the heliopause to the unexpectedly rich structure of the local interstellar medium.

We unpack what Voyager 1 and Voyager 2 have taught us about charged particles, magnetic fields, and cosmic rays beyond the Sun’s protective bubble, and why those measurements have upended earlier ideas about where the Solar System truly ends. Spilker also reflects on the mission’s extraordinary longevity, the ingenuity required to keep the spacecraft communicating across the vastness of space, and what Voyager’s legacy means for future journeys between the stars.

Then, in What’s Up, Bruce Betts, chief scientist at The Planetary Society, places Voyager in context, showing how long-lived missions shape the bigger picture of space science and why observing longer can lead to some of our most profound discoveries.

Discover more at: https://www.planetary.org/planetary-radio/2026-voyagers-and-the-heliopause

What does it really mean to enter interstellar space, and what have we learned since humanity first crossed the invisible boundary between our Sun and the stars?
In this episode of Planetary Radio, we explore the science of the heliosphere and the realm beyond with Linda Spilker, project scientist for the Voyager mission at NASA Jet Propulsion Laboratory. Drawing on decades of experience with the twin spacecraft, Spilker shares how Voyager reshaped our view of the Solar System&rsquo;s outer frontier, from the nature of the heliopause to the unexpectedly rich structure of the local interstellar medium.
We unpack what Voyager 1 and Voyager 2 have taught us about charged particles, magnetic fields, and cosmic rays beyond the Sun&rsquo;s protective bubble, and why those measurements have upended earlier ideas about where the Solar System truly ends. Spilker also reflects on the mission&rsquo;s extraordinary longevity, the ingenuity required to keep the spacecraft communicating across the vastness of space, and what Voyager&rsquo;s legacy means for future journeys between the stars.
Then, in What&rsquo;s Up, Bruce Betts, chief scientist at The Planetary Society, places Voyager in context, showing how long-lived missions shape the bigger picture of space science and why observing longer can lead to some of our most profound discoveries.
Discover more at:&nbsp;<a href="https://www.planetary.org/planetary-radio/2026-voyagers-and-the-heliopause">https://www.planetary.org/planetary-radio/2026-voyagers-and-the-heliopause</a>

Linda Spilker, project scientist for the Voyager mission, explains what Voyager has revealed about the heliopause and the Solar System’s outer edge.

Comparing the rivers of Earth, Mars, and Titan

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