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 ...
Jan 14, 2023•1 hr 31 min
For a cosmologist like me, "cosmic dust" is a thing that's in the way, confounding our data about the pristine Universe, and it's a thing to be understood so that it can be properly subtracted out. But the old saying, that "one astronomer's noise is another astronomer's data," proves to be more true than ever with cosmic dust, as how it's produced, where it came from, and how it comes together to form planets, molecules, and eventually creatures like us, are some of the most essential elements n...
Dec 10, 2022•1 hr 31 min
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 tho...
Nov 12, 2022•1 hr 27 min•Ep. 87
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 star...
Oct 08, 2022•1 hr 23 min•Ep. 86
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 witho...
Sep 10, 2022•1 hr 27 min•Ep. 85
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...
Aug 20, 2022•1 hr 29 min
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 ...
Jul 03, 2022•1 hr 40 min
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 ...
Jun 12, 2022•1 hr 40 min
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 ...
May 08, 2022•1 hr 33 min
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 fr...
Apr 09, 2022•1 hr 40 min
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 fasc...
Mar 19, 2022•1 hr 38 min
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 intell...
Feb 06, 2022•1 hr 32 min
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 oth...
Jan 09, 2022•1 hr 34 min
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 wavelengt...
Dec 18, 2021•1 hr 31 min
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 colle...
Nov 06, 2021•1 hr 33 min
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 i...
Oct 09, 2021•1 hr 32 min
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 o...
Sep 20, 2021•1 hr 53 min
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. B...
Aug 06, 2021•1 hr 33 min
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 to...
Jul 10, 2021•1 hr 19 min
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 nearb...
Jun 05, 2021•1 hr 30 min
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...
May 10, 2021•1 hr 31 min
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 ...
Apr 10, 2021•1 hr 32 min
If you look out at the Universe and measure all the matter out there, including stars, gas, dust, plasma, black holes, etc., it simply doesn't add up. You can't explain the gravitational effects you see with the known particles of the Standard Model alone. But even if you add in the one extra ingredient of cold, collisionless dark matter, it only fixes everything to a certain extent. In particular, the small-scale structures of the Universe, on the scales of individual galaxies and below, have a...
Mar 06, 2021•1 hr 30 min
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...
Feb 14, 2021•1 hr 39 min
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 a...
Jan 11, 2021•1 hr 23 min
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 s...
Dec 13, 2020•1 hr 54 min
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 do...
Nov 22, 2020•1 hr 24 min
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 ad...
Oct 12, 2020•1 hr 24 min
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 astron...
Sep 25, 2020•1 hr 51 min
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 ...
Aug 30, 2020•1 hr 16 min
