The LIUniverse with Dr. Charles Liu

Are there really exoplanets with where it rains ruby and emerald raindrops? How do we measure the atmospheres of exoplanets light years away?

To find out, Dr. Charles Liu and co-host Allen Liu welcome Dr. Munazza Alam of the Space Telescope Science Institute. The STScI performs science operations for the Hubble Space Telescope, the James Webb Space Telescope, and the Nancy Grace Roman Space Telescope when it launches in 2026.

As always, though, we start off with the day’s joyfully cool cosmic thing. On Feb 24, 2026, the Vera C. Rubin Observatory activated the alert system it will use to notify astronomers of noteworthy events and sent out 800,000 alerts on that single day!

Munazza tells us about how she studies the atmospheres of exoplanets like Wasp 121-b, a gas giant thought to have ruby and sapphire rain. Dr. Alam describes exoplanets with surface oceans made of magma, and she and Chuck talk about the importance of plate tectonics.

You’ll hear about Hot Jupiters, Super-Earths, and Sub-Neptunes – and the theories about why we don’t have any of them in our solar system despite the fact that they’re incredibly common in the Milky Way galaxy.

Then it’s time for audience questions, which for this episode come from students at Notre Dame Academy on Staten Island, where Munazza is an alum. Not only does past guest Dr. Betty Jensen teach there, as well, but she was a critical influence on Munazza’s career path. (You can listen to our episode with Dr. Jensen here.)

The first question is from Charlotte, who asks, “How far have we gone in space?” Munazza, Allen, and Chuck discuss Voyager 1, which at a current distance of nearly 16 billion miles is the man-made object that has gone furthest from Earth.

Next up, Gabby asks, “What was the best advice you were given when you were preparing for college?” Dr. Alam’s answer: Pick something you enjoy and are good at - in spite of any pressure you might get from friends, family, and others.

A second piece of advice Munazza got was to maintain your breadth, i.e., developing other interests besides your primary focus. For Munazza, that was art and writing, and she shares some of her art later in the show.

Finally, Gisella asks if it was hard picking a college. Dr. Alam shares her process, with the caveat that it might not be good advice for everyone.

Charles and Munazza reflect on the tradition of scientific exploration, observation, discovery and analysis of which she’s part. Munazza recounts the excitement when JWST observations of transmission spectra of the exoplanet Wasp 39b confirmed their predictions – and also detected something unexpected: sulfur dioxide in the atmosphere of the planet which is a by-product of photochemistry between light from its star and water molecules in the atmosphere of the planet.

Finally, Chuck asks Munazza to share some of her art. She shows us one of the first paintings she ever did, a peacock, and tells us a little about it and a portrait she has displayed at the Lowell Observatory.

If you’d like to know more about what Dr. Alam is up to, you can follower her on LinkedIn or visit her website .

We hope you enjoy this episode of The LIUniverse, and, if you do, please support us on Patreon.

 

Credits for Images Used in this Episode:

Artist impression of Wasp 121-b, an exoplanet thought to have ruby and sapphire rain. – Credit: NASA, ESA, Q. Changeat et al., M. Zamani (ESA/Hubble)

Quake epicenters Digital Tectonic Activity Map of the Earth (DTAM). – Credit: NASA/Goddard Space Flight Center

Illustration comparing the sizes of sub-Neptune exoplanets TOI-421 b and GJ 1214 b to Earth and Neptune. – Credit: NASA, ESA, CSA, Dani Player (STScI)

Illustration of the inferred size of the super-Earth CoRoT-7b (center) in comparison with Earth and Neptune. – Credit: Creative Commons / Aldaron

Location of the Voyager 1 and Voyager 2 spacecraft. – Credit: NASA/JPL-Caltech

JWST transmission spectra of the exoplanet Wasp 39b. – Credit: NASA, ESA, CSA, Joseph Olmsted (STScI)

Radial velocity method to detect exoplanets. – Credit::ESA

Transit method for discovering exoplanets (animation). – Credit: NASA PlanetQuest

Artist's concept of WASP-107b, a gas giant, orbiting a highly active K-type star about 200 light-years from Earth. – Credit: ESA/Hubble, NASA, M. Kornmesser

 

CHAPTERS

00:00 - We welcome Dr. Munazza Alam of the Space Telescope Science Institute

02:50 - Joyfully cool cosmic thing: Vera C. Rubin Observatory Alert System

07:00 - How Do We Know What Exoplanets Are Like?

10:37 - The Importance of Plate Tectonics

11:45 - Hot Jupiters, Super Earths, and Sub-Neptunes

19:56 - How Far Have We Gone In Space, i.e., Where is Voyager now?

22:44 - Best advice when preparing for college?

25:32 - Was it hard picking a college?

31:00 - Confirming Theories and Discovering the Unexpected

36:33 - Munazza Alam Shares Her Painting of a Peacock

38:49 - What data and measurements are used to study exoplanets?

Can the physics you learned in High School take you to the stars? Who is behind many of your favorite pictures of space? What is it actually like to live and work in space? You might be surprised to know how much of it comes down to the physics you probably learned in class and thought to yourself, “When will this ever be useful?”

To answer those questions and more, Dr. Charles Liu and co-host Allen Liu welcome Dr. Don Pettit –NASA astronaut, astrophotographer, chemical engineer, and genuinely one of the most interesting people alive, who was also a science consultant for the movie Project Hail Mary. As you’ll see, the complex physics of space could be critical to your future endeavors in the world of tech, space, and astrophysics.

As always, though, we start off with the day’s joyfully cool cosmic thing, which was the famous DART mission (Double Asteroid Redirection Test). It’s a mission where NASA crashed a spacecraft into a small asteroid (Dimorphos) to see if they could literally change the orbit of an asteroid in space. This mission was successful, changing the asteroid’s orbit by nearly 30 mins. This is certainly joyfully cool, as it shows we can take planetary defense measures to change the path of an impending asteroid.

Throughout the episode, Don, Chuck, and Allen ping pong back and forth with the following topics:

Why he chose chemical engineering (and how that led to becoming an astronaut by consistently choosing passion and innovation over money)

Whether being an astronaut is even worth it financially

How cities look different from orbit over time (yes, you can literally see lighting technology evolve)

The physics behind astrophotography from space (and why those images look so insane)

How astronauts drink coffee in zero gravity!

Just wait, there is even more that we dive into: from lunar bases, to Antarctica meteorite hunts, to a casual mention of driving a lunar rover simulator like it’s nothing.

There’s a lot here that feels huge and abstract, but also weirdly human, like choosing passion over money, or just wanting your morning espresso in space. While Don always had a love for chemistry, he ultimately pursued chemical engineering because he thought he wouldn't be able to get a good job without higher ed (relatable or what?). Then he got a PhD anyway, following his passion.

Don also discusses the coffee cup he invented, which is widely used in space and lets you drink espresso like normal. He designed a cup that lets astronauts drink normally in zero gravity using fluid physics.

Toward the end of the episode, he talks about going to Antarctica to collect meteorites and what that tells us about the chemistry of space.

During this episode, Don’s intrinsic love for creation and scientific innovation shines through. If you like physics, space, or just hearing someone explain complicated things in a way that actually makes sense, you’ll absolutely love this.

If you want to know more about Dr. Don Pettit, you can find him on NASA’s website. For the latest updates on his many projects and dazzling astrophotography, check out his Instagram @astro_pettit. (We’ve included some of those photos in the episode - just another reason to watch on YouTube!)

We hope you enjoy this episode of The LIUniverse, and, if you do, please support us on Patreon.

 

Credits for Images Used in this Episode:

Photo of asteroids Didymos and Dimorphus, NASA’s DART mission target. Credit: NASA/Johns Hopkins APL

Lunar map depicting craters on the south pole of the Moon. Credit: USGS

Don Pettit taking photos on the International Space Station. Credit: NASA

Chicago as seen from the ISS. Credit: NASA/Don Pettit

Burj Khalifa, the world’s tallest building, as seen from the ISS. Credit: NASA/Don Pettit

Sao Paulo, Brazil, at Night, April 12, 2003 as seen from the ISS. Credit: NASA/Don Pettit

Star trail time exposure, taken for approximately 30 minutes during orbital night, assembled from multiple 30 second exposures. Credit: NASA/Don Pettit/Babak Tafreshi

The first prototype of Don Pettit’s capillary cup. Credit :NASA

Astronaut Samantha Cristoforetti drinking from Don Pettit’s cup on the ISS. Credit: NASA

ANSMET meteorite hunters in Antarctica. Credit: NASA

Cross-section of a carbonaceous chondrite, the 4.5-billion-year-old Allende meteorite formed along with the solar system. Credit: AMNH/Creative Commons

Spaceborne - Don Pettit’s photography book. Credit: Don Pettit / Press Syndication Group

 

Special thanks to Eleanor Adams for writing this episode description.

 

 

CHAPTERS

0:00 - Introduction of Astronaut Don Pettit

3:19 - Asteroid Defense Explained (DART Mission & Saving Earth)

10:49 - Don Pettit’s Early Life

14:50 - How Much Does It Pay to Be an Astronaut?

17:11 - What It’s Really Like Living in Space for Months

19:49 - Physics Behind Astrophotography: LEDs and Light Pollution

30:00 - Space Coffee Cup Invention

41:00 - Astrochemistry and Antarctica

How do we find exoplanets? What is the Milky Way’s “Thick Disk” and what makes it so special? To find out, Dr. Charles Liu and co-host Allen Liu welcome Harvard astronomer Dr. Victoria DiTomasso, who has discovered an exoplanet system that includes exoplanet HD60079 b, which she sometimes calls “Bubbles.”

As always, though, we start off with the day’s joyfully cool cosmic thing, a paper just recently published about the exoplanet Teegarden Star b. Dr. DiTomasso explains the difference in exoplanet research between the observational studies she does and the theoretical modeling represented in the paper.

She goes on to discuss recent, exciting theoretical work coming out of UCLA that posits that rather than have our water brought to Earth by comets, we started out as a larger, sub-Neptune planet with a larger hydrogen-helium envelope that we’ve lost over time. This is a pattern seen in some exoplanets, especially given the fact that Super Earth and sub-Neptune planets are the most common types of planets we’ve found, yet we have none in our solar system.

After we find out why a planet Chuck studied was called Flagellan, it’s time to find out how Victoria goes looking for exoplanets, and how she found Bubbles – with an assist from a team of citizen scientists. You’ll learn about using the transit method for discovering exoplanets and identifying potential targets with TESS, the Transiting Exoplanets Survey Satellite and other instruments.

Dr. DiTomasso explains the differences between the Milky Way’s younger “Thin Disk,” the older “Thick Disk,” and the oldest of all, the Milky Way’s “Halo.” Victoria studies the chemistry of stars to categorize them and their planets by age. She’s found 4 stars in the thick disk that have “Hot Jupiters” so far, which is more impressive when you learn that we only knew about one before her work.

Then it’s time for a question from the audience. Grace asks, “Has the environment ever been as bad as it is now, and can it heal by itself?” Chuck, Allen and Victoria discuss changing environments on exoplanets and on Earth, the difference between long and short term change, and the possibility of recovery.

Finally, Chuck asks Victoria what she does outside of astronomy, and we learn all about her new hobby, crocheting. Don’t miss her show and tell, which includes Fred, the cutest crocheted dinosaur to ever appear on The LIUniverse. Victoria also talks about her other hobby, visiting museums – especially art museums. If you’re watching this episode on YouTube, you get to see one of her current favorite exhibits, which consists of semi-abstracted felted wool sculptures of creatures and supernatural beings (yōkai) at the MassArt Museum (MAAM) in Boston.

If you’d like to know more about Dr. Victoria DiTomasso, you can find her on LinkedIn . But to see her latest telescope photos that she took during her observing trip to the Canary Islands, check out her Instagram @victoriaditomasso. (We’ve included some of those photos in the episode - just another reason to watch on YouTube!)

We hope you enjoy this episode of The LIUniverse, and, if you do, please support us on Patreon.

Credits for Images Used in this Episode:

Radial velocity measurements graphic depicting the Radial velocity method to detect exoplanets. – Credit: ESA.

Artist concept of the exoplanet Teegarden's Star b, also known as Teegarden b. – Creative Commons/ Bubblesong.

Illustration comparing sizes of sub-Neptune exoplanets with Earth and Neptune. – Credit: NASA, ESA, CSA, Dani Player (STScI).

Transit method for discovering exoplanets (animation). – Credit: NASA PlanetQuest.

All-sky image showing the flat plane of the Milky Way galaxy. – Credit: E. L. Wright/UCLA, The COBE Project, DIRBE, NASA.

Illustration of the Milky Way’s halo. – Credit: Halo stars: ESA/Gaia/DPAC, T Donlon et al. 2024; Background Milky Way and Magellanic Clouds: Stefan Payne-Wardenaar.

Masako Miki's "Midnight March" features semi-abstracted felted wool sculptures of creatures and supernatural beings (yōkai) at the MassArt Museum (MAAM) in Boston. – Credit: Masako Miki/MAAM

Photos from Victoria DiTomasso’s observing trip to the Canary Islands. – Credit: @victoriaditomasso on Instagram.

 

CHAPTERS

00:00 - Intro and Let’s Meet Dr. Victoria DiTomasso

03:53 - Joyfully Cool Cosmic Thing of the Day: Exoplanet Teegarden Star B

06:20 - Super Earth and Sub-Neptune Exoplanets

12:46 - The Discovery and Naming of Bubbles the Exoplanet

20:32 - The Difference Between Milky Way’s Thin Disk, Thick Disk, and Halo

27:58 - Audience Question: Has the Environment Ever Been this Bad?

36:51 - Crocheted Dinosaurs and Giant Felt Museum Creatures

45:14 - Victoria DiTomasso’s Observing Trip to the Canary Islands

 

#LIUniverse #CharlesLiu #AstronomyPodcast #VictoriaDiTomasso #Exoplanets

How do stars die? And what happens when they do? To find out, Dr. Charles Liu and co-host Allen Liu welcome Dr. Ashley Villar, who teaches astronomy at Harvard and whose team studies supernovas as they happen.

As always, though, we start off with the day’s joyfully cool cosmic thing, the release of a set of new Hubble Space Telescope images of the Crab Nebula and the pulsar at its center. Needless to say, it’s a great start to an episode about a team of scientists who actually study the moment a star explodes and the immediate aftermath.

Ashley explains how they have been able to use LIGO, the gravitational wave detector, as a sort of early warning detector that twice gave them enough time to set up their instruments to observe the explosion over the next few hours and days as it unfolds.

Professor Villar talks about how neutron star mergers and magnetars may be the source of heavy elements like gold and uranium. Or, as Chuck says, “A gold-filled smoke ring puffing off of a highly spinning, highly magnetic neutron star - what a great picture that would be.”

Ashley is looking forward to how the Vera Rubin Observatory is going to change the observation of these events. In the process of explaining, Professor Villar answers an audience question from Jamison, who asks how often stars explode in space. It turns out, in our observable universe, there’s a supernova every 2 seconds! We currently detect about 10,000 of these explosions every year - Vera Rubin will be able to detect 10,000 of these explosions in just two weeks.

In order to get a handle on this flood of data, Dr. Villar and her team will be looking for these exotic physics needles in a haystack using machine learning models to look for patterns and abnormalities and “go fishing.”

Charles asks Ashley for her take on AI and whether we should be afraid of it or not.(And yes, take the opportunity to plug co-host Allen Liu’s forthcoming book, “The Handy Artificial Intelligence Answer Book.”) Allen and Ashley discuss the difference between how a chatbot like ChatGPT operates and how she trains her models.

There was a second part to Jamison’s question about exploding stars: Are we in any danger. Dr. Villar explains that when we just look at our Milky Way, supernovas occur only once a century, so we’re not in any danger.

Next, Jessie asks, “How do we know the universe is infinite?” Our answer is, we don’t. That doesn’t stop us from discussing it, though, and the conversation takes us to, among other places, the Nazca lines in Peru and the quantum effect that creates iridescent blue butterfly wings. (You can read the scientific research mentioned in the episode here: https://www.nature.com/articles/ncomms8959)

We end with a discussion about supernovas, neutrinos, space dust, gamma ray bursts, and what kind of event it would take to interrupt the normal activities of space telescopes like the James Webb Space Telescope or the Vera Rubin and hijack them for a disruptive observation. And we get a book recommendation from Ashley, “Katabasis” by R. F. Kuang, about a grad student who journeys to hell to get a letter of reference from her deceased advisor.

If you’d like to know more about what Professor Villar is up to, you can check out her lab’s website at http://astrotimelab.com/.

We hope you enjoy this episode of The LIUniverse, and, if you do, please support us on Patreon.

Credits for Images Used in this Episode:

New Hubble mosaic of the Crab Nebula. – Credit: William P. Blair et al 2026 ApJ 997 81

Previous Hubble photo of the Crab Nebula. – Credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)

The Vera Rubin Observatory. – Credit: RubinObs/NOIRLab/SLAC/NSF/DOE/AURA/P. Horálek (Institute of Physics in Opava), CC BY 4.0

Nazca line “The Condor”. – Credit: Photo by Roger Canals

Blue butterfly wings in an electron microscope. – Credit: Radislav A. Potyrailo et al.

Aragonite plates in a shell. – Credit:  Fabian Heinemann

SN 1987A (Bright central “star”). – Credit: European Southern Observatory

Artist’s illustration of Gamma Ray Burst jets. – Credit: International Gemini Observatory/NOIRLab/NSF/AURA/J. da Silva; Image processing: M. Zamani (NSF's NOIRLab)

CHAPTERS:

00:00 - Welcome to The LIUniverse

02:14 - Joyfully Cool Cosmic Thing of the Day - Hubble Crab Nebula Images

07:06 - Neutron Star Mergers, Magnetars, and Space Gold

09:18 - How Often Do Stars Explode?

12:35 - Can AI Help Us Find Supernovas?

17:11 - Are We In Danger From Exploding Stars?

19:48 - How Do We Know the Universe Is Infinite?

24:01 - How Does Quantum Physics Impact Color in Butterflies and Supernovas?

31:16 - How to Hijack a Space Telescope

How do planetary systems form? If you wanted to observe them, where would you look and what would you look for?

To find out, Dr. Charles Liu and co-host Allen Liu welcome Luke Keller, professor of Astronomy and Physics at Ithaca College, who together with his team has identified 9 of these early solar systems.

As always, though, we start off with the day’s joyfully cool cosmic thing: a recently published paper that determined that at any given time, it is likely that a couple of extrasolar objects like 3I/ATLAS and Oumuamua would be present in our solar system. The real issue is detecting them.

For context, Luke, whose science has focused over the years on finding debris from solar systems, explains how protoplanetary discs can eject matter that ends up orbiting that star. He’s especially fond of cosmic dust, “the catalyst for the formation of planets and asteroids and comets…”

Then it’s time for a question for Luke from the audience, from Elisa: “I heard that the James Webb Space Telescope sees infrared light. How does that work? Does that mean it couldn't see the Sun?”

Luke breaks down the various wavelengths of light and our Sun. He also explains how the JWST works and why it never looks at the sun.

It turns out that Luke has built a variety of astronomical instruments including imaging and spectroscopic tools with for large observatories. He’s also used information from instruments like JWST in his studies of the formation of stars and solar systems.

Luke explains how his teams search for preplanetary solar systems, what they’re looking for, and where they’re currently looking: associations of stars in the direction of the constellations Taurus, Scorpius and Chamaeleon. All told so far Luke and his team have identified 9 of these early solar systems. He then breaks down the current thinking on how planetary systems form from clouds of dust. He explains some of the processes that involves, along with the types of planets that may form.

For our next audience question, Joan asks, “What do you think is the most interesting constellation?” Luke picks two: first, Ursa Major, aka “The Big Dipper,” because he grew up in Alaska and saw it all the time – along with “auroras all the time.” The second constellation he picks is Orion, aka “The Hunter,” because it contains some of the closest star forming regions of our galaxy.

Luke unpacks the difference between “watching the sky” and “observing the sky” – and why he encourages the latter to both his students and the general public. And before the episode is over, we get to hear about Luke’s live show, Spacetime, where he collaborates with poet David Gonzalez and guitarist Álvaro Domene in a stage performance that’s equal parts astrophysics, poetry, and music.

If you’d like to know more about Luke’s show, Spacetime, check it out at https://spacetimeshow.org/.

We hope you enjoy this episode of The LIUniverse, and, if you do, please support us on Patreon.

Credits for Images Used in this Episode:

Image of a young sun-like star encircled by its planet-forming disk of gas and dust. – Credit: NASA/JPL-Caltech edited by Invader Xan.

Artist's impression of the interstellar interloper 1I/ʻOumuamua making a visit to our solar system. – Credit: NASA, ESA, and J. Olmsted and F. Summers (STScI).

Spectral distribution of sunlight. – Credit: Creative Commons / Rhwentworth.

The Taurus-Auriga association, also known as the Taurus-Auriga molecular clouds, is a stellar association located around 140 parsecs (420 ly) from Earth in the constellation of Taurus. It is the nearest large star formation region to Earth. – Credit: ESA/Herschel/NASA/JPL-Caltech; acknowledgement: R. Hurt (JPL-Caltech)

The constellation Taurus as seen by the naked eye. The constellation lines have been added for clarity. – Credit: Creative Commons/ Till Credner - Own work, A Visual Guide to the Constellations.

Artist’s impression of a young star surrounded by a protoplanetary disk in which planets are forming. – Credit: European Southern Observatory.

Illustration comparing the sizes of various exoplanets with Earth, Mercury and the Moon. – Credit: NASA's Goddard Space Flight Center.

The constellation Ursa Major as it can be seen by the unaided eye.– Credit: Creative Commons / Till Credner - Own work: AlltheSky.com.

Composite image comparing infrared and visible views of the famous Orion nebula and its surrounding cloud, an industrious star-making region located near the hunter constellation's sword. The picture at left was taken with the Infrared Array Camera on board NASA's Spitzer Space Telescope, and the picture at right is from the National Optical Astronomy Observatory, headquartered in Tucson, Ariz. – Credit: NASA/JPL-Caltech/Univ. of Toledo/NOAO.

Image showing Betelgeuse (top left) and the dense nebulae of the Orion molecular cloud complex. – Credit: Creative Commons / Rogelio Bernal Andreo