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Starts With A Bang podcast

Starts With A Bang podcast

By Ethan Siegel

The Universe is out there, waiting for you to discover it.
There’s a cosmic story uniting us.
We’re determined to bring it to everyone.
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Starts With A Bang #97 - Tiny Galaxies and Us

Starts With A Bang podcastSep 02, 2023

Starts With a Bang #99 - Varying and evolving stars

Starts With a Bang #99 - Varying and evolving stars

You might not think about it very often, but when it comes to the question of "how old is a star that we're observing," there are some very simple approximations that we make: measure its mass, radius, temperature, and luminosity (and maybe metallicity, too, for an extra layer of accuracy), and we'll tell you the age of this star, including how far along it is and how long we have to go until it meets its demise.

This also operates under a simple but not-always-accurate assumption: that all stars of a given mass and composition have the same age-radius and radius-temperature-luminosity relationships. That simply isn't true! Stars vary, both over time as they evolve and also from star-to-star dependent on their rotation and magnetism. It's a funny situation, because just a few years ago, people had declared stellar evolution as a basically "solved" field, and now it turns out that we might have to rethink how we've been thinking about the most common classes of stars of all!

To help us explore this topic, I'm so pleased to welcome Dr. Lyra Cao (pronounced "Tsao" and not "Cow" in case you were interested) to the program, where she helps walk us through what we're only now learning about stars: particularly young stars, low-mass stars, and rapidly rotating stars. If you know nothing about stellar evolution, this will be a treat for you, as you won't have to un-learn a massive amount of information to make sense of the Universe!

(This image shows a temperature profile of star HD 12545, which unlike our Sun, doesn't just have a small number of tiny sunspots on it, but is dominated by a massive, star-spanning starspot that covers approximately 25% of its surface. Many stars, including low-mass, young, and rapidly rotating stars, have enormous sunspots that can play a major role in the habitability of their systems. Credit: K.Strassmeier, Vienna, NOIRLab/NSF/AURA)

Nov 11, 202301:42:07
Starts With A Bang #98 - The Line Between Star And Planet

Starts With A Bang #98 - The Line Between Star And Planet

Out there in the Universe, there's a whole lot more than simply what we find in our own Solar System. Here at home, the largest, most massive object is the Sun: a bright, hot, luminous star, while the second most massive object is Jupiter: a mere gas giant planet, exhibiting a small amount of self-compression due to the force of gravity.

But elsewhere in the Milky Way and beyond, numerous classes of objects exist in that murky "in-between" space. There are stars less luminous and lower in mass: the K-type stars as well as the most numerous star of all: the red dwarf. At even lower masses, there are brown dwarf stars, possessing various temperatures ranging from a little over ~1000 K all the way down to just ~250 K at the ultra-cool end.

These "in-between" objects, not massive enough to be a star but too massive to be a planet, have their own atmospheres, weather, and a variety of other properties. The thing that limits our knowledge of them, at present, is merely our own instruments. That's why, on this edition of the Starts With A Bang podcast, I'm so pleased to welcome Dr. Brittany Miles, an expert on ultra-cool brown dwarfs and a specialist in instrumentation technology. If you were ever curious about these "in between" objects, you won't want to miss this journey to the frontiers of modern astronomical science!

(This graphic compares a Sun-like star with a red dwarf, a typical brown dwarf, an ultra-cool brown dwarf, and a planet like Jupiter. While brown dwarfs are neither star nor planet, they're fascinating objects in their own right, and very much part of the cosmic story uniting us all. Credit: MPIA/V. Joergens)

Oct 14, 202301:32:23
Starts With A Bang #97 - Tiny Galaxies and Us

Starts With A Bang #97 - Tiny Galaxies and Us

When we look at our nearby Universe, it's easy to recognize our own galaxy and the other large, massive ones that are nearby: Andromeda, the major galaxies in nearby groups like Bode's Galaxy, the group of galaxies in Leo, and the huge galaxies at the cores of the Virgo and Coma Clusters, among others. But these are not most of the galaxies in the Universe at all; the overwhelming majority of galaxies are small, low-mass dwarf galaxies, and if we want to understand how we formed and where we came from, it's these objects that we need to be studying more intensely.

So what is it that we already know about them? What has recent research revealed about these tiny galaxies in the nearby Universe, both inside and beyond our Local Group, and what else can we look forward to learning in the relatively near future? Join me for a fascinating discussion with Prof. Mia de los Reyes of Amherst College, as we dive into the science of the tiniest galaxies of all, and what they can teach us about our cosmic history as a whole!

(This image shows a map of stars in the outer regions of the Milky Way, from the northern celestial hemisphere, with several galactic streams visible. The color-coding indicates the distance to the stars, and the brightness indicates the density of stars in that patch of sky. In the white circles are faint companions of the Milky Way discovered by the SDSS: only two are globular clusters, the rest are all dwarf galaxies. Credit: V. Belokurov and the Sloan Digital Sky Survey)

Sep 02, 202301:38:50
Starts With a Bang #96 - Detecting the Cosmic Gravitational Wave Background

Starts With a Bang #96 - Detecting the Cosmic Gravitational Wave Background

We all knew, if Einstein's General Theory of Relativity were in fact the correct theory of gravity, that it would only be a matter of time before we detected one of its unmistakable predictions: that all throughout spacetime, a symphony (or cacophony) of gravitational waves would be rippling, creating a cosmic "hum" as all of the moving, accelerating masses generated gravitational waves. The intricate monitoring of the Universe's greatest natural clocks, millisecond pulsars, would be one potential way to reveal this cosmic gravitational wave background.

But not many expected that here in 2023, we'd be announcing the first robust evidence for it already, and that future studies will reveal precisely what generates it and where it comes from. Yet here we are, with pulsar timing taking center stage as the second unique method to directly detect gravitational waves in our Universe!
For this edition of the Starts With A Bang podcast, I'm so pleased to welcome Dr. Thankful Cromartie to the show, where she guides us through the gravitational wave background, the science of pulsar timing arrays, and the underlying astrophysics of the objects that we monitor with them: millisecond pulsars. It's a fascinating story and one that's more accessible than ever with this latest podcast, and I hope you learn as much as I did listening to it!

(The illustration shown here maps out how merging black holes from all across the Universe generate ripples in spacetime, and as those ripples pass across the lines-of-sight from a millisecond pulsar to us, those signals create timing variations across this natural array. For the first time, in 2023, we've detected strong evidence indicating the presence of this cosmic gravitational wave background. Credit: Daniëlle Futselaar ( / Max Planck Institute for Radio Astronomy)

Aug 12, 202301:41:33
Starts With A Bang #95 - Supermassive Black Holes and more

Starts With A Bang #95 - Supermassive Black Holes and more

Sometimes, it's hard to believe we've come as far as we have, scientifically, in such a short period of time. We only began accumulating the first very strong evidence for supermassive black holes during the 1990s, and yet here we are, less than 30 years later, studying them, their effects, and their environments all across the Universe: from the present day to less than 1 billion years after the Big Bang.

We now believe that nearly every galaxy out there in the Universe not only produces black holes from the corpses of the most massive stars within them, but also supermassive ones that resides at the centers of these cosmic objects. Every once in a while, these supermassive black holes accrete matter and devour some of it, becoming active in a spectacular display. Just as we're learning all about how the Universe grows up in terms of stars, atoms, and gas, we're starting to learn how these supermassive black holes evolve and grow up, too.

Here to guide us through the latest and greatest scientific discoveries, I'm so pleased to welcome Dr. Allison Kirkpatrick onto our show. Allison is a professor at the University of Kansas and specializes in supermassive black holes, from X-ray to radio observations and well beyond. Join us on this exciting journey to the heart of one of our greatest cosmic mysteries, and see what it's like at the frontiers of science here on Starts With A Bang!

(This image is the first mid-infrared image of Stephan's Quintet ever taken by the James Webb Space Telescope. The galaxy at the topmost-right of the image displays a brilliant spikey pattern: evidence of a supermassive black hole that had never been revealed prior. Credit: NASA, ESA, CSA, STScI)

Jul 15, 202301:38:28
Starts With A Bang #94 - Dark Energy And Cosmic Growth

Starts With A Bang #94 - Dark Energy And Cosmic Growth

We have a pretty good idea of both what's in our Universe and how it grew up. But it's only because we have several different, completely independent lines of evidence that point to the same consensus picture that we actually believe that our Universe is 13.8 billion years old and composed of a mix of normal matter and radiation, but is dominated by dark matter and dark energy on the largest of cosmic scales.

In particular, we form large, cosmically bound structures on the scales of galaxies and galaxy clusters, but on larger scales, dark energy and the expanding Universe dominate, working to drive everything apart. The story of how we've come to know this information about the Universe and how we're using both old and new techniques to push the our understanding further is the subject of this edition of our podcast. It features PhD candidate Karolina Garcia, who's kind enough to walk us through a variety of types of research that all serve the same end: to reveal the story of the Universe and how it grew up to be the way it is today. Take a listen; you won't regret it!

(This image shows a series of structure-formation simulations: at low resolution, medium resolution, and superior/high resolution, for both cold dark matter and fuzzy dark matter models. If we can measure the Universe precisely and accurately enough, we can distinguish between these types of models, contingent on whether we simulate it to great enough precision. Credit: M. Sipp et al., MNRAS (submitted), 2023)

Jun 17, 202301:39:15
Starts With A Bang #93 - Mars From The Ground

Starts With A Bang #93 - Mars From The Ground

One of the most exciting possibilities for life beyond Earth doesn't require us going very far. While Mercury and the Moon have no atmosphere and Venus is an inferno-esque hellscape, Mars offers a tantalizing possibility for a new line of life, independent of Earth, here in our Solar System. With the same raw ingredients and more than a billion years of a watery, wet past, Mars could have had, or might even still have today, some form of life on its surface.

Part of the reason Mars is so exciting for us is that we've been there: at least, robotically, with a series of orbiters, landers, and even rovers. We've seen and learned so much about the red planet, including some tantalizing hints of what might be biological activity. But there's so much more to learn, and we're reaching the limits of what we can accomplish without having human beings walk on the Martian surface.

On this episode of the Starts With A Bang podcast, we're joined by Mars expert Dr. Tanya Harrison, who's worked on three generations of Mars Rovers and is a strong advocate for a variety of future missions to Mars. Join us for this fascinating conversation where she lays out what we know, what remains uncertain, and what we'll need to do if we want to take those next, critical steps. (And, as a bonus, she corrects one or two of my misconceptions along the way!)

(This image shows the Mars Perseverance rover in one of its "selfie-mode" images, where its own tracks and the Ingenuity rover are both visible in the background. Credit: NASA/JPL-Caltech/ASU/MSSS/Seán Doran)

May 06, 202301:33:30
Starts With A Bang #92 - Type Ia Supernovae

Starts With A Bang #92 - Type Ia Supernovae

Back in the 1990s, observations of type Ia supernovae were the key data set that led astronomers to conclude that the Universe's expansion was accelerating, and some new form of energy, now known as dark energy, was permeating the Universe. Over the past ~25 years, those observations have gotten so good that we now have a tension within the expanding Universe, as different methods of measuring the expansion rate yield two different sets of mutually incompatible results.

What's remarkable is that this result is robust even though we're still somewhat uncertain as to exactly how these type Ia supernovae occur. The original scenario, put forth by Chandrasekhar nearly a century ago, still has its adherents, but the evidence appears very strong that approaching and reaching a "mass limit" beyond which atoms are unstable can only explain a small fraction of white dwarf behavior. Instead, a new paradigm dominated by merging white dwarfs may explain nearly all type Ia supernova explosions!

On this episode of the Starts With A Bang podcast, we talk to UC Berkeley astronomer Dr. Ken Shen, a theorist whose expertise lies in type Ia supernovae, and learn how just the last 20 or so years have led to a revolution in how we conceive of these "standard candles" in the Universe, and just what observations might soon lead us to know, for certain, how these cosmic events are truly triggered!

(The titular illustration shows two merging white dwarfs, the preferred theoretical mechanism for the triggering of some, and perhaps most or even nearly all, type Ia supernovae. The double detonation scenario, where a "detonation" event on the surface propagates to the core and causes a detonation that leads to total destruction of the stellar remnant, it one very intriguing theoretical possibility. Credit: D. A. Howell, Nature, 2010)

Apr 08, 202301:45:57
Starts With A Bang podcast #91 — Hypermassive neutron stars

Starts With A Bang podcast #91 — Hypermassive neutron stars

When stars are born, they can come with a wide variety of masses. But there are only a few ways that stars can die, and only a few types of remnants that can be left behind: white dwarfs, neutron stars, and black holes. Neutrons stars and black holes are most frequently created from core-collapse supernova events: the deaths of massive stars. Somewhere, even though we're not sure exactly where it is, there's a dividing line between "what makes a neutron star?" and "what makes a black hole?" Somewhere out there, there's a heaviest neutron star, and someplace else a lightest black hole.

But the dividing line might not be so clean, after all. It turns out that when neutron stars merge, they can form another neutron star, a black hole, or a third case: an in-between scenario. In this third case, you can temporarily form a hypermassive neutron star: a neutron star that's too massive to be stable, but that collapses in short order to a black hole, but only after persisting as a neutron star for a detectable amount of time.

To help guide us through the science of hypermassive neutron stars, I'm so pleased to welcome Dr. Cecilia Chirenti to the show, a joint scientist at NASA Goddard and the University of Maryland, College Park. There's a whole lot of cutting-edge science right at (and even over) the horizon of what we know today, and you won't want to miss this information-rich episode!

(This image shows the illustration of a massive neutron star, along with the distorted gravitational effects an observer might see if they had the capability of viewing this neutron star at such a close distance. Credit: Daniel Molybdenum/flickr and raphael.concorde/Wikimedia Commons)

Mar 11, 202301:37:13
Starts With A Bang #90 - How Galaxies Grow Up

Starts With A Bang #90 - How Galaxies Grow Up

One of the great advances of 20th and 21st century science has been, for the first time to show us two things: how the Universe began and what the Universe looks like today. The modern frontier is all about the in-between stages: how did the Universe grow up? How did it go from particles to atoms to the first stars and galaxies to the modern Milky Way, Local Group, and Universe-at-large? It's a question that, the more deeply we answer it, the greater the number of details that emerge, requiring us to make a special effort to pin each one down.

For this episode, I'm so pleased to welcome Dr. Ivanna Escala to the podcast: an expert in how stars and stellar properties within the Local Group can reveal not only its stellar history, but its history of galactic assembly. While the Milky Way has had a few major mergers, its most recent was a whopping ~10 billion years ago. Andromeda, our Local Group's other large galaxy, has a remarkably different story: with a major merger that occurred only 2-4 billion years ago!

Have a listen and enjoy, and thanks to Avenues Online for being our sponsor!

(This image, assembled from very long wavelengths of light of the neighboring Andromeda Galaxy, shows features within Andromeda's galactic disk as well as the gas clouds of neutral hydrogen found in Andromeda's galactic halo. By examining these features, as well as streams and stars in and around Andromeda, we can reconstruct precisely how this galaxy came to be the way it is today. Credit: NRAO/AUI/NSF, WSRT)

Feb 11, 202301:37:14
Starts With A Bang #89 - The active threat of the Sun

Starts With A Bang #89 - The active threat of the Sun

For life on Earth, there's no more important source of energy than the Sun; without it, it's doubtful that life would have arisen on Earth, and it certainly wouldn't have evolved to give rise to the wild diversity of biological organisms seen today. But the Sun is more than just a constant source of heat and light; it also emits particles, and there's a darker side to that activity: flares, coronal mass ejections, and the threats this space weather poses to living planets like our own.

It turns out that for technologically advanced civilizations like our own, the threats that arise from the Sun are far greater and more dangerous than at any time prior in Earth's history, and despite the knowledge we have of what the Sun can do to the Earth, we're woefully unprepared for the inevitable. Thankfully, there are not only people studying it, but many of them are also fighting and advocating for solutions and planetary protection, including Sierra Solter, a plasma physicist specializing in solar plasmas, who joins us on this edition of the Starts With A Bang podcast.

Welcome to a glorious 2023, and may we learn the needed lessons for what must be done before we're left with the sad alternative of simply picking up the pieces!

(This illustration shows a massive space weather event, larger than a typical solar flare, known as a surface mass ejection. Although SMEs have the capacity to entirely destroy a planet, they're thankfully limited to occurring on red supergiants, a class of star that will never include our Sun or anything it will evolve into. Credit: NASA, ESA, Elizabeth Wheatley (STScI))

Jan 14, 202301:31:04
Starts With A Bang #88 - From dust till cosmic dawn

Starts With A Bang #88 - From dust till cosmic dawn

Dec 10, 202201:30:53
Starts With A Bang #87 - AGNs From The South Pole

Starts With A Bang #87 - AGNs From The South Pole

The supermassive black holes at the centers of galaxies is a tremendously interesting area of research, advancing rapidly over the past few years. While most of these observations focus on either high-energy or radio emissions from them, there's a recent push to see what these objects are doing in other wavelengths of light, as well as how they vary in time.

Once, it was thought that supermassive black holes would become "activated" at a certain point in time, would remain on for hundreds of thousands or even millions of years, and would then turn-off. But our observations have shown us that there are remarkable variations in what types of light and energy these objects emit over time, and with new studies being conducted at the South Pole and other places studying the Universe in millimeter-wavelength light, we're about to get an unprecedented amount of high-quality data.

Here to guide us through what we've learned so far about these active galaxies and where this research might take us in the future is Dr. John Hood, a postdoctoral research associate at the University of Chicago. It's a wild ride here at the frontiers of science, and I hope you enjoy every minute of it!

(In this artistic rendering, a blazar is accelerating protons that produce pions, which produce neutrinos and gamma rays when they decay. Lower-energy photons are also produced, allowing blazars, a form of Active Galactic Nucleus (AGN) to be seen all across the electromagnetic spectrum. In recent years, we’ve advanced to the point where we’re detecting neutrinos from billions of light-years away, beginning with blazar TXS 0506+056. Credit: IceCube collaboration/NASA)

Nov 12, 202201:27:07
Starts With A Bang #86 - Stars In The Universe

Starts With A Bang #86 - Stars In The Universe

All throughout the Universe, we see stars and galaxies everywhere we look. But as we look to greater and greater distances, we're only seeing the light that's the easiest to see: the ones from the brightest, most visible objects. But the most numerous objects of all are exactly the opposite: less luminous, smaller, and lower in mass. How can we hope to find and catalogue them all if they're the hardest ones to find?

The answer lies in measuring the closest stars to us. If we can measure the stars that persist in our own backyard, cataloguing them and taking as complete a census as possible, we can then combine what else we know about stars and starlight and the environments in which new stars form to reconstruct precisely what we believe is out there: not just here-and-now, but elsewhere and all throughout cosmic time.

Here to bring us up to speed on how this attempt to catalogue and categorize the stars in the Universe, I'm so pleased to welcome PhD candidate at Georgia State University Eliot Vrijmoet to the show, who takes us on a fascinating journey to the edge of our knowledge, and from there we'll peer over the horizon to what just might come next. Enjoy the latest episode of the Starts With A Bang podcast!

Star density maps of the Gaia Catalogue of Nearby Stars. The Sun is located at the centre of both maps. The regions with higher density of stars are shown; these correspond with known star clusters (Hyades and Coma Berenices) and moving groups. Each dotted line represents a distance of 20 parsecs: about 65 light-years. (Credit: ESA/Gaia/DPAC - CC BY-SA 3.0 IGO)

Oct 08, 202201:22:56
Starts With A Bang #85 - Planetary Formation

Starts With A Bang #85 - Planetary Formation

Although it seems like a long time ago, it was as recent as the early 1990s that we had no idea whether planets in the Universe were universal, common, uncommon, or even exceedingly rare. While certain data sets once seemed to indicate that practically every star in the Universe had planets around it, we now know that isn't true at all. Many stars, perhaps even most of them, have planets, but plenty of others don't. In addition, the number and types of planets that exist, including planets without parent stars at all, are still under investigation, and the field of planet formation has become extremely active.

With new data coming in from infrared and radio observatories, including JWST and ALMA, we're learning so much about the planets that form in the Universe, including what conditions they form under and what the various important, dominant considerations are. Here as our latest guest on the Starts With A Bang podcast, to help us disentangle what's known from what remains a curiosity, is Dr. Kamber Schwarz, postdoctoral research associate at MPIA Heidelberg.

There's still so much to learn, but wow, how much we know today compared to the early 1990s is astounding. Enjoy this look at the frontiers of what we know about how planets are made, and I hope it leaves you wondering about what else we'll learn in the very near future!

[This two-toned image shows an illustration of the protoplanetary disk around the young star FU Orionis, which was imaged multiple times by the Hubble Space Telescope but years apart. The disk has changed, indicating that it's entering a more advanced stage of evolution, as planets form and the material available for forming and growing them evaporates, sublimates, and is otherwise blown away. (Credit: NASA/JPL-Caltech)]

Sep 10, 202201:27:05
Starts With A Bang #84 - Cosmological Mysteries

Starts With A Bang #84 - Cosmological Mysteries

From the earliest stages of the hot Big Bang up through and including the present day, one cosmic picture is sufficient to describe practically everything we observe: the Lambda-Cold Dark Matter (ΛCDM) cosmological model. With a mix of dark matter, dark energy, normal matter, photons, and neutrinos, we can not only model, but can simulate the Universe from the earliest times and the smallest scales up through to the present and the full scale of the observable Universe.

In most cases, theory and observation match, and spectacularly so. But there are a few current points of tension: cosmological mysteries, that range from the expansion rate of the Universe to small-scale structure formation to the link between the pre-Big Bang Universe and our current dark-energy-caused accelerated expansion.

Where are we, how far have we come, and how far do we still have to go? I'm so pleased to welcome Dr. Santiago Casas, who specializes in many of the same sub-areas of cosmological physics I specialized in about a decade earlier, to our podcast. In this nearly 90-minute long episode, we cover a slew of fascinating topics in more depth and detail than normal, and I hope you enjoy the extra-deep dive into some of the weediest areas of modern cosmology!

This image shows a 15 million light-year long structure that arises from a detailed simulation of the cosmic web and how galaxies, galaxy clusters, and cosmic filaments form on the largest scales of all. Although this theoretical simulation, like many aspects of our standard cosmological models, largely agrees with our observations, there are points of tension that must not, despite the successes, be ignored. (Credit: Jeremy Blaizot, SPHINX project,
Aug 20, 202201:28:53
Starts With A Bang #83 - The Longest Gravitational Waves

Starts With A Bang #83 - The Longest Gravitational Waves

Since the advanced LIGO detectors first began operating in 2015, we've not only directly detected our first gravitational wave signals from merging objects in the Universe, we've observed close to 100 such systems that have emitted detectable gravitational wave signals. All of them to date, however, are the result of short-period, low-mass stellar remnants that have inspiraled and merged into one another. The most massive black holes, at least in gravitational waves, remain elusive.

If all goes well, however, that won't be the case for long. At the centers of very massive galaxies, there's often not just one supermassive black holes, but multiples. Ultramassive binary black holes, in fact, send such energetic ripples through spacetime that they ought to distort, in measurable ways, the arriving radio signals from pulsars distributed all throughout the Milky Way. By monitoring these pulsars extensively through a series of timing arrays, we just might be able to extract information about the longest-wavelength gravitational waves that fill the Universe.

Here to walk us through what we're looking for, how we're conducting this science, what we've seen so far, and what the prospects are for gravitational wave direct detection in an entirely new regime is Dr. Caitlin Witt, who I'm so pleased to welcome to the Starts With A Bang podcast. We've got a 100 minute spectacular for this episode, and you won't want to miss a single moment of it!

Image: This illustration show how the Earth, itself embedded withing spacetime, sees the arriving signals from various pulsars delayed and distorted by the background of cosmic gravitational waves that propagate all throughout the Universe. The combined effects of these waves alters the timing of each and every pulsar, and a long-timescale, sufficiently sensitive monitoring of these pulsars can reveal the gravitational signals. (Credit: Tonia Klein/NANOGrav)
Jul 03, 202201:40:27
Starts With A Bang #82 - JWST And Infrared Astronomy

Starts With A Bang #82 - JWST And Infrared Astronomy

It's now been nearly a full six months since the JWST was launched, and we're on the cusp of getting our first science data and images back from some 1.5 million kilometers away. There are all sorts of things we're bound to learn, from discovering the farthest galaxies of all to examining details in faint, small objects to searching for black holes in dusty galaxies and a whole lot more. But what's perhaps most exciting are the things we're going to find that we aren't expecting, simply because we've never looked in this particular fashion before.

I'm so pleased to welcome two guests to the show: Research Professors Dr. Stacey Alberts and Dr. Christina Williams both join me this month, and we have a far-ranging conversation about infrared astronomy and all that we're poised to learn from exploring the Universe in the infrared as never before. If you're already excited about JWST and what we're going to learn from it, wait until you listen to this episode!

(Image: Although Spitzer (launched 2003) was earlier than WISE (launched 2009), it had a larger mirror and a narrower field-of-view. Even the very first JWST image at comparable wavelengths, shown alongside them, can resolve the same features in the same region to an unprecedented precision. This is a preview of the science we'll get. Credit: NASA and WISE/SSC/IRAC/STScI, compiled by Andras Gaspar)
Jun 12, 202201:39:59
Starts With A Bang podcast #81 - The Local Bubble

Starts With A Bang podcast #81 - The Local Bubble

When we look out at the Universe, what we see is typically what we think of: the points of light. Depending on the scales we're looking at, this can come in the form of stars, galaxies, or even clusters of galaxies, but it's almost always information that comes to us in some form of electromagnetic radiation, or light. But sometimes, light can be just as informative for what either isn't there or how it's been affected by the various media that it's passed through!

In the case of our own cosmic backyard, a new study from earlier this year, 2022, revealed something spectacular and entirely unexpected: that the Sun sits at the center of a ~1000 light-year wide structure known as the Local Bubble, itself just about 15 million years old but containing all of the nearest young star clusters to us. In fact, the star Aldebaran, one of the brightest in the sky, helped "blow" this bubble in the interstellar medium!

It's the very first episode of the Starts With A Bang podcast ever to feature multiple guests, and I'm so pleased to welcome Drs. Catherine Zucker, Alyssa Goodman, and João Alves to the podcast, all three of whom helped make this knowledge possible! I hope you enjoy the listen, and it's a 90 minute spectacular you won't regret spending your time on!


Discovery paper:

Press release:


Interactive visualization:

(This visualization shows the Sun's location at the center of a structure about 1000 light-years across known as the Local Bubble. Recent episodes of star-formation have led to a series of new star clusters, shown in the illustration, which have formed a bubble and pushed it out. The Sun has only entered this region recently, and just happens to be at the center now, when we're looking. Credit: Leah Hustak/STScI)
May 08, 202201:33:18
Starts With A Bang #80 - The Cosmos, James Webb, and Beyond

Starts With A Bang #80 - The Cosmos, James Webb, and Beyond

Have you ever wondered how it is that we know all we do about galaxies? How they formed, what they're made of, how we can be certain they contain dark matter, and how they grew up in the context of the expanding Universe? In any scientific discipline, we have the things we know and can be quite confident in, the things that we think we've figured out but more data is required to be certain, and the things that remain undecided given the current evidence: things over the horizon of the present frontiers.

Fortunately, we have the ability to scrupulously identify which aspects of galaxy formation and evolution fall into each category, and to walk right up to the edge of our knowledge and peer over that ever-expanding horizon. Joining me for this episode of the Starts With A Bang podcast is scientist Arianna Long, Ph.D. candidate at the University of California at Irvine and soon-to-be Hubble Fellow at the University of Texas at Austin. With the advent of ALMA and the James Webb Space Telescope, in particular, we're poised to seriously push back the frontiers of the unknown, and you can get the insider's view of exactly what we'll be looking for and how. This is one episode you certainly won't want to miss!

Image: This view of a portion of the DREaM simulated galaxy catalog provides a snippet of sky that might correspond, statistically, with what James Webb expects to see. This particular snippet showcases an incredibly rich region of relative nearby galaxies clustered together, which could provide Webb with an unprecedented view of galaxies magnified by strong and weak gravitational lensing. (Credit: Nicole Drakos, Bruno Villasenor, Brant Robertson, Ryan Hausen, Mark Dickinson, Henry Ferguson, Steven Furlanetto, Jenny Greene, Piero Madau, Alice Shapley, Daniel Stark, Risa Wechsler)
Apr 09, 202201:39:43
Starts With A Bang #79 - The Far Infrared Universe

Starts With A Bang #79 - The Far Infrared Universe

Every time we've figured out a different way to look at the Universe, going beyond the capabilities of our own meagre senses, we've opened up an opportunity to learn something new about what's out there. Although optical astronomy and near-infrared astronomy are arguably the most popular ways to view the Universe, with James Webb soon to bring the mid-infrared Universe into view as never before, we shouldn't forget about the value of other, more distant wavelengths of light.

One of the most fascinating sets of data that we can collect is in the far-infrared, where gas heated to just a few tens of Kelvin shines, but where much hotter, even ionized gas can emit very special hyperfine transitions. Mapping out these regions of space helps us understand what's going on beyond mere star-formation or other violent events, and a series of remarkably specific observational techinques are, quite arguably, how we're obtaining the most valuable information of all in this part of the electromagnetic spectrum.

Joining the Starts With A Bang podcast to help guide us through the topic of far-infrared astronomy is Dr. Jessica Sutter, an astronomer at NASA Ames who's part of the USRA and who works with the SOFIA telescope, a one-of-a-kind far-infrared observatory that can do what no ground-based nor space-based observatory can. Have a listen, and I hope you wind up learning as much as I did!

(The featured image shows galaxy NGC 7331 along with other members of its galactic group, including the prominent galaxies NGC 7335, 7336, 7337, and 7340. Credit: Vicent Peris/c.c.-by-2.0)
Mar 19, 202201:38:16
Starts With A Bang #78 - From Failed Stars To SETI

Starts With A Bang #78 - From Failed Stars To SETI

When you start looking at the Universe, you realize that there are more signals out there than are simply generated by stars. On the one hand, you have astrophysical objects like gas, dust, plasma, as well as stellar corpses and their remnants. But there are also failed stars that didn't quite make it to the nuclear fusion stage that defines our Sun and the other stars like it: brown dwarfs.

Beyond that, there may also be signatures of planets like Earth out there: planets inhabited by an intelligent civilization. It's of paramount importance, when asking the biggest questions, to make sure that we aren't fooling ourselves, but that's where projects like SETI and Breakthrough Listen come in: to help us extract legitimate science where "wishful thinking" has the potential to lead us in precisely the most dangerous direction: the possibility of fooling ourselves.

I'm so pleased to welcome Ph.D. Candidate Macy Huston to the podcast, as we explore the less commonly seen side of the Universe: from exoplanets to brown dwarfs to the search for extraterrestrial intelligence. With the advent of the James Webb Space Telescope, we really are going to see a tremendous change in what we know!
Feb 06, 202201:32:15
Starts With A Bang #77 - Stellar Destruction

Starts With A Bang #77 - Stellar Destruction

Some stars, as they go through their life cycles, will die of natural causes. They'll burn through their fuel until they can fuse elements no longer, and then will die, becoming a white dwarf below a certain mass threshold, or experiencing a core-collapse supernova that leaves behind a neutron star, a black hole, or perhaps something even more interesting above that mass threshold. But some stars, while just going about their lives, can suffer a wildly different fate: they can be murdered by other objects in the Universe. Stellar destruction can take many forms and can give off many different unique signals, and it's only by examining a wide range of the electromagnetic spectrum, as well as other types of sources, that we can decode what's actually going on across the Universe.

I'm so pleased to welcome Dr. Yvette Cendes to the program, who specializes in radio astronomy and the behavior of exotic objects that change their behavior over time: transient signals. There's so much to explore and I hope you enjoy this fascinating 90 minute discussion right here on the Starts With A Bang podcast!

(Credit: Alak Ray, Nature Astronomy, 2017; ACTA/ALMA/ESO/Hubble/Chandra composite)
Jan 09, 202201:34:25
Starts With A Bang #76 - Supermassive Black Holes

Starts With A Bang #76 - Supermassive Black Holes

When it comes to the black holes that populate the Universe, they range from the very tiny, of only ~3 solar masses or so and with event horizons that span only a few kilometers, all the way up to the incredibly supermassive, many billions of times as massive as our Sun, with event horizons on the scale of the entire Solar System. These black holes are fascinating not only for how they form and exist, but how they impact and shape the entire galaxies that they inhabit. At all different wavelengths, from X-ray to radio, as well as in gravitational waves, we're only starting to uncover the previously elusive science about these cosmic behemoths, and while we're all the richer for it today, it's fascinating to consider what questions we'll be answering decades down the line, too.

Come have a listen to all of these topics and much, much more as we go on a fascinating journey concerning supermassive black holes with Dr. Adi Foord of Stanford, and expose the mysteries of the largest single structures in the entire Universe!

(Image credit: NASA)
Dec 18, 202101:30:46
Starts With A Bang #75 - Instruments And Mega - Cameras

Starts With A Bang #75 - Instruments And Mega - Cameras

You know how it works, right? Point your telescopes at the sky, collect the data, and then send it off to the scientists for analysis and to compare with the predictions of your theories. Only, if that's what you do, you'll miss a crucial first step: you have to handle your data correctly. That means understanding the nuances of your telescope, the sensitivities of your instruments and optics across different filters and wavelengths, and so many other considerations before that data you've collected could ever be responsibly used for any scientific purposes at all.

But this is not a hopeless task; there are entire careers in telescope and instrument support sciences that, in many ways, are the unsung heroes of the entire enterprise of astronomy. In this edition of the Starts With A Bang podcast, I'm so pleased to get to bring Dr. Heather Fleweling onto the show, where she talks about her experience and expertise doing precisely this for observatories such as Pan-STARRS, which she helped build herself, to the Canada-France-Hawaii Telescope (CFHT), where she currently works, specializing in the MegaPrime instrument. Get a behind-the-scenes peek at a corner of astronomy that most people don't even know exists!
Nov 06, 202101:32:55
Starts With A Bang #74 - Galaxy Clusters And Their Environments

Starts With A Bang #74 - Galaxy Clusters And Their Environments

In the science of astronomy, it's important to see both the forest and the trees. Galaxy clusters, in many ways, serve as both. They're rich environments with stars, gas, dust, dark matter, black holes and more. The diversity of stars and stellar populations found within them, as well as found within galaxies of different shapes, sizes, and properties within those clusters, are part of a remarkable and coherent cosmic story. But sometimes the cosmic story can help us understand what's going on in these environments, the converse of the way we normally think about it: where we use the environment to learn about the universe.

Come take a fascinating journey into these cosmic behemoths that are the gathering grounds for the greatest collections of large galaxies in the universe, and enjoy a delightful conversation with Gourav Khullar as we go along on this wild ride!

(Image credit: ESA/Hubble and NASA, H. Ebling)
Oct 09, 202101:32:00
Starts With A Bang #73 - Ocean Worlds And So Much More

Starts With A Bang #73 - Ocean Worlds And So Much More

If you want to understand the origin of life in the Universe, you have three basic ways to do it. One is to search for intelligent aliens directly: through a program such as SETI. Another is to search for life in Solar Systems beyond our own: looking for bio-signatures, or perhaps bio-hints, on extraterrestrial worlds many light-years away. But within our own Solar System, there are a plethora of worlds, including the ice-and-liquid-rich bodies we have, that are fascinating candidates for life of non-Earth origin.

There's so much to explore and so many different aspects of what's out there that I went into an incredibly far-ranging conversation with our podcast guest, planetary scientists and NExSS postdoc Dr. Jessica Noviello, that we wound up talking for nearly two full hours, and still couldn't cover everything we wanted to! Still, it was an amazing conversation for me and I hope it is for you, too. Enjoy it!

(Image credit: NASA/JPL/Ted Stryk, of Europa with its uniquely curved stripes, for the Galileo mission.)
Sep 20, 202101:53:23
Starts With A Bang #72 - The Central Cores Of Galaxies

Starts With A Bang #72 - The Central Cores Of Galaxies

Practically every galaxy in the Universe has a supermassive black hole at their core. Ranging from millions to many billions of solar masses, these cosmic behemoths are capable of behaving as engines: accreting and accelerating matter to tremendous speeds and temperatures, where they emit enormous amounts of radiation. Galaxies can remain in this active state for hundreds of millions of years, where they appear to us as active galactic nuclei or quasars, depending on their specific properties.

But why are some galaxies active while others aren't? How long will the active ones we see remain active, and will some of the inactive ones turn on? What about flares? As it turns out, there's a powerful connection between the surrounding galaxy, the processes occurring at the core, and the activity levels of the central black hole. Here to help us put it all together is Dr. Yashashree Jadhav, who takes us on a fascinating and far-ranging discussion about black holes, gas, stars, and much, much more! Enjoy it all on this edition of the Starts With A Bang podcast!

(The image here is a multiwavelength view of the galaxy Centaurus A: the closest active galaxy to the Milky Way. Image credit: X-ray: NASA/CXC/SAO; Optical: Rolf Olsen; Infrared: NASA/JPL-Caltech.)
Aug 06, 202101:33:24
Starts With A Bang #71 - Rare Stars And Stargazers

Starts With A Bang #71 - Rare Stars And Stargazers

Like everything in the Universe, stars are born, they live a little while, and then they die. But despite their similarities in terms of where they come from and what they're made of, these objects can have an enormous variety of fates that they experience, and there are some fascinating intermediate and near-final states along the way. Beyond that, the unique stories of the people who made those key discoveries that have brought us to where we are can help us understand exactly how we pieced together the stellar picture of our Universe's history together.

I'm so pleased to welcome Emily Levesque, professor at the University of Washington, author of The Last Stargazers, and enthusiastic lover of the Universe beyond planet Earth to the podcast. This ~80 minute episode was one of my favorites, and showcases Emily's knack for combining her vast knowledge of astronomy with her passion for sharing those stories with the entire world. Have a listen on the latest installment of the Starts With A Bang podcast!

(Image credit: Emily Levesque / Perimeter Institute.)
Jul 10, 202101:19:13
Starts With A Bang #70 - The Accelerating Milky Way

Starts With A Bang #70 - The Accelerating Milky Way

When we think about the Universe as a whole, the accelerations that objects experience from our perspective are overwhelmingly due to the expansion of the Universe. Nearby, however, it's the local gravitational effects of nearby masses that dominate. Within our own Local Group, we've been able to discover that the Milky Way is not some quiet, massive spiral just going about its own business, but rather that it's being tugged in a variety of ways from the large masses around it, including a nearby galaxy that was only discovered in very recent years: Antlia 2.

This is one of the most exciting detective stories we've gotten to uncover in recent years, as the resolution of this mystery showcases how improved, high-resolution data taken over long periods of time can enable us to witness galactic changes, directly, on the timescale of a single human lifetime. Here to walk us through what we know, how we know it, and what comes next is Prof. Sukanya Chakrabarti of the Rochester Institute of Technology, and I think you'll really enjoy what turned out to be a deep and far-ranging conversation about astronomy right in our own cosmic neighborhood!

(Image credit: V. Belokurov and A. Smith; acknowledgement: Markus and Gail Davies; Robert Gendler)
Jun 05, 202101:29:38
Starts With A Bang #69 - Machine Learning In Astronomy

Starts With A Bang #69 - Machine Learning In Astronomy

When you think about how astronomy works, you probably think about observers pointing telescopes at objects, collecting data about their properties, and then analyzing that data to determine what those objects are truly like, and to infer what they can teach or show us about the Universe. But that's a rather old-fashioned way of doing things: one that's contingent on there being enough astronomers to examine all of that data manually. What do we do in this new era of big data in astronomy, where there aren't enough astronomers on Earth to even look at all of the data by hand? The way we deal with it is fascinating, and involves a mix of statistics, classical analysis and categorization, and novel techniques like machine learning and simulating mock catalogues to "train" an artificial intelligence. Perhaps the most exciting aspect is how thoroughly the best of these applications continuously outperform, in both quality and speed, any of the manual techniques we've used previously. Here to walk us through this exciting and emerging field of machine learning in astronomy is Sankalp Gilda, PhD candidate and astronomer from the University of Florida. We've got a great 90 minutes here for you, so buckle up and enjoy the ride! (Image credit: VLT Survey Image / ESO; Acknowledgement: Aniello Grado & Luca Limatola)
May 10, 202101:31:29
Starts With A Bang #68 - Pulsars, Polarization And More

Starts With A Bang #68 - Pulsars, Polarization And More

Swarming through our own galaxy, we've detected quite a few bizarre objects: pulsars. These rapidly spinning neutron stars are only a few kilometers across, yet contain more mass than our entire Sun. They're denser than a uranium atom's nucleus, and some of them possess the strongest magnetic fields in the known Universe. The fastest-spinning one known rotates about its axis 766 times per second, and they can travel at up to ~65% the speed of light. And outside of the ones we've found, we fully expect there might hundreds of millions or even as many as a billion such neutron stars hanging out simply in our Milky Way galaxy.

But they also emit their own light, and a good chunk of that light is polarized, giving us an incredible set of information. In addition, by coordinating the pulse times of many different pulsars, we can not only detect gravitational waves, but can detect the types of waves generated by objects that LIGO and even LISA will never see. I'm so pleased to welcome Haley Wahl, pulsar specialist and PhD candidate, onto the show, and I hope you enjoy what turned out to be a fantastic conversation!

(Image credit: NanoGRAV Collaboration.)
Apr 10, 202101:32:03
Starts With A Bang #67 - Astroparticles And Dark Matter
Mar 06, 202101:30:27
Starts With A Bang #66 - XENON And Astroparticle Physics

Starts With A Bang #66 - XENON And Astroparticle Physics

Have you ever wondered what it's like to work as a small (but vital) part of a large collaboration, where hundreds or even thousands of experimental scientists get together to produce an experiment far larger or more complex than any one person could oversee on their own? Have you ever wondered where the line is between physics and astronomy, and whether it even makes sense to have a line at all in the case of astroparticle physics? And have you ever wished that people would be more honest about the recent toxic experiences that they had when they were starting out that are still relevant to young people in those shoes today?

I'm so pleased to have such a remarkable discussion with astrophysicist Niko Sarcevic (pronounced "SHAR-chev-itch" when comes out of my mouth) that's was not only far ranging but incredibly enjoyable for me. I hope you like listening, and if you want to listen to me absolutely botch describing the XENON experiment (which doesn't use the lead shielding I described; that was a different detector: SuperCDMS!), it's well-documented for everyone to hear!

(Image credit: M. van der Wild, using Niko's phone, of the then-under-construction electric field cage that Niko Sarcevic designed and built for the Time Projection Chamber (TPC) for the XENON collaboration.)
Feb 14, 202101:38:56
Starts With A Bang #65 - Ultracool Dwarfs

Starts With A Bang #65 - Ultracool Dwarfs

You might have thought that if we were going to find life anywhere in the Universe, our best bet would be to look at stars like our Sun, on account of the tremendous success of Earth. It's a good bet, for sure, but did you know that the Sun is brighter and more massive than 95% of stars in the Universe? And that down at the low-mass end of the spectrum, the most common type of objects out there are ultracool dwarfs: low-mass red dwarfs and even brown dwarfs? They have rocky planets around them and could be our first candidate Earth-sized worlds for direct imaging, and are incredible scientific objects of study all on their own.

What do you want to know about them? I'm so pleased to welcome PhD candidate Anna Hughes onto the Starts With A Bang! podcast, and to share her knowledge and wisdom and enthusiasm with all of you. Here's how we start 2021 with a bang, and I hope you enjoy it!
Jan 11, 202101:23:07
Starts With A Bang #64 - Galaxies Without Dark Matter

Starts With A Bang #64 - Galaxies Without Dark Matter

Over the past 2 years, an exciting development has finally arisen: scientists have measured a large number of small, diffuse galaxies exquisitely well, and have finally found their first candidate galaxies that appear to have no dark matter at all. Whereas large cosmic structures typically have dark matter-to-normal matter ratios of 5-to-1, smaller structures typically have higher ratios, as star formation will kick some of the normal matter out but leave the dark matter intact. However, there should be a second type of galaxy: stars without dark matter, as tidal interactions can rip the normal matter out and keep it out. But these structures are easy to destroy, and so shouldn't persist for very long.

How, then, did we find a galaxy that both appears to have no dark matter and also appears to have not formed any new stars in ~7 billion years or more? While the science is still ongoing, I'm so pleased to welcome Dr. Mireia Montes onto the program, whose recent paper may have just solved the mystery. Have a listen and enjoy the show; there's a lot of astronomy in here for you to enjoy!

(Image credit: Montes et al., 2020, ApJ.)
Dec 13, 202001:53:57
Starts With A Bang #63 - Exoplanets, TESS, And Beyond

Starts With A Bang #63 - Exoplanets, TESS, And Beyond

Over the past 30 years, we've gone from zero exoplanets to thousands. With each new generation of telescopes, observatories, and scientists, we build upon our previous finds to make enormous advances that go beyond what any one person could ever produce. The ESA's Gaia mission has surveyed more than a billion stars, identifying the closest ones that would make potentially great targets for NASA's James Webb Space Telescope, if they had potentially habitable planets around them. NASA's TESS is doing the preliminary work of observing these stars, most of which are red dwarf (M-class) stars, to find which ones actually have interesting planets that transit across their parent star's face.

So far, we've found some fascinating candidates, some of which just might be humanity's first discovery of biosignatures beyond our Solar System if we get lucky. This month, we're so fortunate to be joined by astronomer and TESS scientist Emily Gilbert, a Ph.D. candidate who specializes in exoplanets. (And who has the delightful Twitter handle: @EmDwarf.)

Come learn where we are, what we know, and where this rapidly evolving scientific field is headed today!

Nov 22, 202001:23:32
Starts With A Bang #62 - Black Holes And ALMA

Starts With A Bang #62 - Black Holes And ALMA

It was only back in the early 2000s that scientists were struggling to identify and weigh the small number of supermassive black holes that we'd been able to identify in the known Universe, but the past 15-20 years have led to a revolution in what we know about them. We've identified tens of thousands of active galaxies, pinned down the masses of some of the closest ones to us through a variety of techniques, and even observed the event horizon of our first black hole directly.

These powerful advances were mainly enabled by superior observatories and instruments, and the spectacular Atacama Large Millimetre/Submillimetre Array (ALMA) of telescopes, which was indispensible to measuring the mass and imaging the event horizon at the core of the largest massive galaxy in our neighborhood: M87.

I'm so pleased to welcome astronomer and Ph.D. Candidate Kyle Kabasares onto the show, where we talk about black holes, mass measurements, ALMA, and the future of black hole-related astronomy! Kyle is also passionate about science outreach, and you can check out his YouTube channel here.

(Image credit: EHT Collaboration; acknowledgement: ESO)
Oct 12, 202001:23:38
Starts With A Bang #61 - Astronomical Instruments And Injustices

Starts With A Bang #61 - Astronomical Instruments And Injustices

When most of us think of astronomy, we think about two types of scientists: the observers who point their telescopes at the sky and collect data, and the theorists who put together the physical rules of the Universe to both make critical predictions for what those observational results ought to yield and to interpret the data that comes in. But in reality, there are other important types of astronomers that we don't talk about frequently: analysts who focus on dealing with these literally astronomical data sets and the people who work on (and with) the instrumentation itself. This includes telescope and instrument builders, telescope operators and system specialists, and many other vital roles.

Additionally, the science of astronomy isn't just about the science itself, but also questions important for the interplay of science and society. Whose land are these telescopes on? What does responsible stewardship look like? Who has access to these facilities, and who has equal (and unequal) access to the career paths of becoming a scientist?

I'm so pleased to have astronomer Jess Schonhut-Stasik on the show, for a wide-ranging discussion about astronomy, from instruments to injustices and how the big questions about science and society are creating not only incredible dilemmas for astronomy, but an incredible opportunity to get things right. Have a listen today, and check out the fabulous Mauna Kea Scholars program that she's involved with here:

(With permission, her email address associated with inquiries about the program is here:

[Image credit: UKIRT / University of Hawaii Institute for Astronomy]
Sep 25, 202001:50:59
Starts With A Bang #60 - The End Of The Dark Ages

Starts With A Bang #60 - The End Of The Dark Ages

When we look out at the Universe today, we see that it's full of stars and galaxies. And yet, we can only see those stars and galaxies because the space between those galaxies and ourselves doesn't block that starlight before it gets to our instruments, observatories, telescopes, and eyes. But early on, that's an enormous problem: there is light-blocking gas and dust, and the record-holder for most distant galaxy ever discovered is still not a pristine, first-generation galaxy at all.

But there are new observatories and cutting-edge techniques that will reveal them, teaching us how the Universe grew up: from a collection of neutral atoms with no stars and galaxies at all to the structure-rich Universe we see today. Joining me on this special, bonus edition of the Starts With A Bang podcast (because don't we all need a bonus?) is extragalactic astronomer and PhD candidate Rebecca Larson from the University of Texas - Austin, in a rich conversation that takes us all the way back to the edge of the Universe as we can observe it.

Find out what lies at, and perhaps beyond, our current cosmic frontiers!

(Image credit: NASA, ESA, and J. Kang (STScI))
Aug 30, 202001:16:26
Starts With A Bang #59 - Active Galaxies

Starts With A Bang #59 - Active Galaxies

When we look out at the galaxies in the Universe, almost all of them have supermassive black holes at their centers: millions or even many billions of times more massive than our Sun is. Most of the time, these black holes are relatively quiet, but every so often, a black hole can be spotted emitting enormous amounts of radiation over a large range of the electromagnetic spectrum. These "active galaxies" come in many different flavors, from blazars to AGNs to quasars and many others, but they're very closely tied to both the age of the Universe and how rapidly a galaxy forms stars.

There's an awful lot that we've learned about these objects, and yet, still so many more mysteries to solve and uncover. This month, as the first of two podcasts, I'm so pleased to bring PhD candidate Alyssa Sokol, from the University of Massachusetts - Amherst, onto the program, as we enjoy a far-reaching conversation that takes us beyond the limits of what we know.

(Image credit: X-ray - NASA, CXC, R.Kraft (CfA), et al.; Radio - NSF, VLA, M.Hardcastle (U Hertfordshire) et al.; Optical - ESO, M.Rejkuba (ESO-Garching) et al.)
Aug 14, 202001:36:40
Starts With A Bang #58 - Gravitational Waves From Space

Starts With A Bang #58 - Gravitational Waves From Space

When it comes to gravitational waves, our terrestrial laser interferometers have provided us with unparalleled success in terms of direct detection. But they have some strong fundamental limits: their laser arms are short; their sensitivity is limited to low-mass, small-radius objects; the signals they detect last for mere seconds, at most. Most importantly, seismic noise, and even the fact that we live on a planet with tectonic plates, place restrictions on how sensitive we'll ever be able to get.

But in space, all of these stories change dramatically, and the upcoming European Space Agency mission LISA is aiming to open up our eyes to a realm of gravitational wave astronomy like we've never experienced before. On this edition of the Starts With A Bang podcast, we're joined by Dr. Ira Thorpe of NASA as we explore the future of gravitational wave astronomy in an entirely new realm: in space!

(Image credit: EADS ASTRIUM)
Jul 17, 202001:19:41
Starts With A Bang #57 - The Universe's Newborn Stars
Jun 12, 202001:06:49
Starts With A Bang #56 - Dark Matter Substructure
May 09, 202001:09:58
Starts With A Bang #55 - The Cataclysmic Deaths Of Stars

Starts With A Bang #55 - The Cataclysmic Deaths Of Stars

When you look up at the sky, most of the points of light we see appear to be fixed. On night-to-night timescales, the distant stars and galaxies, with the exception of a few notable variables, appear to be relatively unchanged. But every once in a while, a spectacular event will occur, giving off a transient signal that outshines a typical star's brightness by factors of many billions. These events fall into many classes: supernovae, gamma ray bursts, and even more exotic events, and part of the fun is uncovering exactly what's going on as we discover these new classes of objects for the first time.

Scientist Anna Ho, PhD candidate at Caltech, is right on the cutting edge of that frontier, and brings us an insider's look at this exciting and rapidly evolving field. Come get the latest on what we know and what we're still learning about the cataclysmic deaths of stars!

(Image credit: Bill Saxton (NRAO/AUI/NSF))
Apr 10, 202001:09:40
Starts With A Bang #54 - The Origin Of Stars

Starts With A Bang #54 - The Origin Of Stars

One of the great challenges for astronomy is to determine, in gory detail, how stars are formed from a mere cloud of molecular gas and dust. Although the general picture is simple, where gravitational collapse leads to protostars that ignite nuclear fusion in their cores, the actual environments where these stars are born have many competing factors at play. Gravitational collapse is only one of them, joined by thermal heating and radiative cooling, magnetic fields and hydrodynamics, as well as stellar winds, ultraviolet radiation, and feedback from a variety of sources.

Here to help us disentangle what's important, where, and when is Ph.D. candidate Mike Chen, an astrophysicist specialized in the formation of stars at the University of Victoria. If you've ever wondered how we actually form stars in our Universe, this edition of the Starts With A Bang podcast is for you!

(Image credit: ESA and the Planck Collaboration.)
Mar 04, 202001:10:30
Starts With A Bang #53 - Exoplanets From Kepler To TESS And Beyond

Starts With A Bang #53 - Exoplanets From Kepler To TESS And Beyond

How many planets are out there in the Universe? How many stars have planets, and what kinds of planets do stars of various types have? How close are we to doing direct imaging, finding whether some of our Earth-like planets are potentially habitable or even inhabited? Are Super-Earths a real thing, or are all of the ones larger than our world more Neptune-like than we care to admit?

We've answered a whole slew of questions about exoplanets that we didn't even know to ask a decade or two ago, and there's so much more happening right now as well as on the horizon. Come get the scoop on the latest Starts With A Bang podcast, featuring the incredible Dr. Jessie Christiansen of NASA's Exoplanet Science Institute!

(Image credit: NASA / TESS)
Feb 07, 202001:03:45
Starts With A Bang #52 - The Thirty Meter Telescope

Starts With A Bang #52 - The Thirty Meter Telescope

The history of astronomy is a history of receding horizons. As we improve our optics, our instruments, and our observing techniques, we can reveal progressively more of the Universe than we've ever seen before. As the 2020s dawn on us, we're preparing to jump from 10 meter-class observatories, which are presently the largest in ground-based optical telescopes, to 30 meter-class ones, with approximately thrice the resolution and ten times the light-gathering power.
There's a tremendous suite of cosmic stories to discover, but the only one of the 30 meter-class observatories to be built in the Northern Hemisphere is facing a tremendous controversy that's been decades in the making. What are the next steps towards building the Thirty Meter Telescope?

The latest edition of the Starts With A Bang Podcast features the TMT's vice president for external relations, Dr. Gordon Squires, and you won't want to miss it!

(Image credit: Thirty Meter Telescope Collaboration)
Jan 09, 202001:21:22
Starts With A Bang #51 - Cosmology At The Edge Of Time

Starts With A Bang #51 - Cosmology At The Edge Of Time

Have you ever wondered what the first moments of our Universe were like? Not just going back towards the hot Big Bang, but at the very first fractions of a second that come after, during, and even before the Big Bang occurs?

It was my pleasure to get to speak to Dan Hooper, astrophysicist, professor, and author of the new book At The Edge Of Time, which is my favorite popular science book of 2019. (Pick up a copy here:

In this fascinating hour+ conversation, we cover topics like dark matter, inflation, and what not only 21st century physics but even 30th century physics might hold. Don't miss it!

(Image credit: Princeton University Press / Dan Hooper.)
Dec 14, 201901:08:44
Starts With A Bang #50: The Hunt For Planet Nine And Beyond

Starts With A Bang #50: The Hunt For Planet Nine And Beyond

What lies out there, in the outer Solar System, beyond the orbit of the last known planet? Up until 1992, you would have said Pluto and its moon (maybe "moons" if you were willing to speculate), but even the existence of the Kuiper belt was doubted by many. Of course, all of that changed with the discovery of many different objects, including the more-massive-than-Pluto world discovered in 2003: Eris. We quickly realized that Pluto was not unique, but one member of a distinct class of objects thoroughly different than the planets. In 2006, we created the "dwarf planet" classification for non-planetary objects that still were Pluto-like.

But more recently, a compelling but controversial idea has emerged: the idea of a Planet Nine that is more massive than even Earth, but lies hundreds of times farther away that we are from the Sun. Both of these achievements, the theorizing of Planet Nine and the Pluto-killing discovery of Eris, come courtesy of the same planetary astronomer: Mike Brown. Dive into a fascinating conversation with him and me right here on the 50th edition of the Starts With A Bang podcast!

(Image credit: Caltech/R. Hurt (IPAC))
Nov 14, 201901:17:55