All things in the cosmos have a lifespan, from the smallest particles to the most ancient suns. Everything has its season. Every season must come to an end. And this episode marks the end of Orbital Path. So, for the last transit of our podcast, Dr. Michelle Thaller and producer David Schulman join NASA astrobiologist Dr. Jen Eigenbrode on a site visit to one of Michelle’s very favorite places at Goddard Space Flight Center. It’s building 29, where NASA builds and tests spacecraft in some of the most extreme conditions found anywhere on earth.  Orbital Path is produced by David Schulman.  
 Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Michelle Thaller. 
 Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance. Image credit: NASA

Asteroids, as the dinosaurs found out, can have big effects on life on Earth.  Sixty-five million years ago, an asteroid crashed into the Yucatán. The impact caused apocalyptic tsunamis and volcanic eruptions. Grit and ash blotted out the sun. It wiped out species that had roamed the Earth for millions of years. Yet asteroid hits also were critical to the origins of life on Earth. Asteroids may well have been the bringers of water, of carbon, even of amino acids — the building blocks of life. That’s a big reason why NASA is on a mission to Bennu. This asteroid is like an ancient fossil of our solar system — largely unchanged since the time the planets formed. In December, after a billion-mile journey, NASA’s Osiris-Rex mission arrives at Bennu. And, for the first time, a spacecraft will try to actually bring back an asteroid sample to Earth. On this episode of Orbital Path, Dr. Michelle Thaller sits down with Dr. Amy Simon — a senior scientist at NASA’s Goddard Space Flight Center, and a key player on the Osiris-Rex mission. Michelle and Amy talk about the mission, Amy’s work to probe the origins of the solar system, and one other thing:  The remote chance that Bennu, someday, could collide with Earth. Orbital Path is produced by David Schulman.  Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance. Image credit: NASA/Goddard/University of Arizona.

To make a black hole, you need to think big. Really big. Start with a star much bigger than the sun — the bigger the better. Then settle in, and wait a few million years for your star to die. That should do the trick, if you want to get yourself a garden-variety black hole. But there’s another kind of black hole. They are mind-boggling in size. And deeply mysterious: Super-massive black holes. Last year, in the journal Nature, a team of astronomers reported finding one with the mass of 800 million suns. It’s the most distant black hole in the known universe. And it’s so ancient, it dates to a time when it seems light itself was only just beginning to move. On this episode of Orbital Path, Dr. Michelle Thaller talks with astrophysicist Chiara Mingarelli — Flatiron Research Fellow at the Center for Computational Astrophysics in New York. Using a special gravitational wave observatory, Dr. Mingarelli is part of a cadre of astronomers hoping ancient super-massive black holes will soon reveal mysteries dating to the dawn of our universe. Orbital Path is produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance. Image credit: NASA artist’s rendering of a super-massive black hole.

On September 15, 2018, the last Delta II rocket lifted off from Vandenberg Air Force base, in California. It carried into orbit IceSat-2 — a satellite equipped with perhaps the most sophisticated space laser ever built.   NASA didn’t put it up there to shoot down rogue asteroids. Instead, it’s taking aim — with exquisite precision — at Earth.   On this episode of Orbital Path, Dr. Michelle Thaller talks with Tom Wagner. He’s been looking forward to the launch of IceSat-2 for a decade. Officially, Wagner is NASA’s Program Scientist for the Cryosphere. That means he studies the frozen regions of the Earth: Antarctica. The Arctic Ocean. The glaciers of Greenland. All places critical to understanding our planet’s changing climate.   From 300 miles above, the six laser beams of IceSat-2 won’t harm even the most light-sensitive earthling, Wagner says. But, as he describes it, the satellite will allow scientists to precisely map the retreat of ice at the poles. And that promises to teach us a great deal about how Earth’s climate will change in the years to come. Orbital Path is produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance. Image credit: NASA

We live our lives in three dimensions. But we also walk those three dimensions along a fourth dimension: time. 

Our world makes sense thanks to mathematics. Math lets us count our livestock, it lets us navigate our journeys. Mathematics has also proved an uncanny, stunningly accurate guide to what Brian Greene calls “the dark corners of reality.”

 But what happens when math takes us far, far beyond what we — as humans — are equipped to perceive with our senses? What does it mean when mathematics tells us, in no uncertain terms, that the world exists not in three, not in four — but in no fewer than 11 dimensions?

 In this encore episode of Orbital Path (previously heard in October 2017), Brian Greene, a celebrated explainer of how our universe operates and the director of the Center for Theoretical Physics at Columbia University, sits down to talk with Dr. Michelle Thaller.  Together they dig into the question of how we — as three-dimensional creatures — can come to terms with all those extra dimensions all around us.  
Orbital Path is produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance. Image by: World Science Festival / Greg Kessler

To hear Leonard Susskind tell it, we are living in a golden age of quantum physics. And he should know. Susskind is a grandee of theoretical physics. In the 1960s, he was one of the discoverers of String Theory. His friends and collaborators over the years include the likes of Nobel Prize winners Gerard ‘t Hooft and Richard Feynman. And, for more than a decade, Susskind engaged in an intellectual clash of the Titans with Stephen Hawking — and came out on top. On this episode of Orbital Path, Dr. Michelle Thaller talks with Susskind about his extraordinary life in physics. And Susskind offers a tantalizing glimpse into his recent work on the holographic principle, which suggests our universe may be a far, far stranger place than humans have yet imagined. Orbital Path is produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance. Image credit: Linda Cicero / Stanford News Service

For a long time, probably as long as we have been gazing up at the night sky, people have been asking ourselves: Are we alone? Is there life out there, anywhere else in the universe? For modern Earthlings, our fascination with extraterrestrial life has focussed on one place in particular: Mars. The planet today is a forbidding, arid place. But billions of years ago, Mars may have had a gigantic ocean. It was, like Earth, just the kind of place you’d think life could get started. Earlier this month, in the journal Science, NASA astrobiologist Dr. Jen Eigenbrode and her team published a stunning discovery. The Curiosity rover on Mars had found rocks that contain organic molecules — the building blocks of life. On this episode of Orbital Path, Dr. Michelle Thaller sits down with Eigenbrode to understand what this discovery really says about the possibility of life on Mars. This episode of Orbital Path was produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance. Image credit: NASA

Zoe is in 8th grade. She’s a student in Mr. Andersen’s Earth science class at a public school in Brooklyn. Lately, she’s been concerned about the future of the planet. Specifically, Zoe has been learning about the phenomenon of planetary dehydration — and she wanted to ask Dr. Michelle Thaller what would happen if Earth lost its water. It’s part of a new Orbital Path project called “Telescope,” where Dr. Michelle Thaller fields astronomy questions from public school students. Michelle says dehydration isn’t anything we’ll have to worry about in our lifetimes. But in 200 million years — not all that long, in astronomical terms — our planet could resemble the desert world of Frank Herbert’s “Dune.” Orbital Path is produced by David Schulman. The program is edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Dr. Michelle Thaller. The music heard in this episode is “Austin 1” by Manwomanchild. Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance. Mars image credit: NASA

Secrets of the universe? A glimpse of the whiteboard in the office of Nobel Prize-winning astrophysicist Adam Riess. Adam Riess was only 41 when he was named a Nobel Prize winner. The Johns Hopkins distinguished professor of astronomy shared in the award for his work on something called “dark energy” — a discovery that over the past 20 years has profoundly shifted our understanding of the universe. Riess made news again recently when he and colleagues working with the Hubble Space Telescope announced new findings about the rate at which the universe is expanding — findings which simply cannot be explained by physics as we know it. It’s weird and profound stuff. Our story begins a century ago, with a riddle posed by a curious part of Einstein’s Theory of General Relativity — something called the “Cosmological Constant.” The fate of the universe just may hang in the balance. This episode of Orbital Path was produced by David Schulman. Our editor is Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance. Image credit: David Schulman

Instead of grappling with the big, cosmic questions that preoccupy adults, this week on Orbital Path we’re doing something different. We’re grappling with the big, cosmic questions that preoccupy kids. It’s part of a new project called “Telescope,” where Dr. Michelle Thaller takes on the really big questions in astronomy—from public school students. In this episode, Michelle fields questions from Mr. Andersen’s Earth Science class at MS 442, a public school in Brooklyn. Sarah Cole asks about creating artificial gravity on spacecraft. And Carter Nyhan wonders whether the stars guiding mariners ancient and modern, were, by the time their light reached the earth, completely kaput. Is the twinkling night sky actually a graveyard of dead stars? Orbital Path is produced by David Schulman. The program is edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Dr. Michelle Thaller. Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance. Image credit: NASA image of the International Space Station, where gravity does, in fact, still apply.

On August 17, 2017, an alert went out. Gravitational wave detectors in Louisiana and Washington state had detected a disturbance from deep space. The effect was subtle — these detectors and a sister site in Italy measure disturbances smaller than a proton. But the evidence was dramatic. And the story they told was truly cataclysmic: A pair of neutron stars had spiraled to their deaths. That apocalyptic collision of two super-dense stars bent the very fabric of space time — just as Einstein had predicted. It sent Gamma rays out into deep space. It created an immense cloud of gaseous gold. And, 130 million years later, astronomers on earth witnessed the final 100 seconds of these two stars’ dance of death. It’s taught us where gold came from, and helped humans understand other intractable mysteries of the universe. In this episode of Orbital Path, Dr. Michelle Thaller speaks with two astronomers who watched this cosmic death tango from the best seats in the house. We’ll hear from Dr. Vicky Kalogera. She’s Director of CIERA — the Center of Interdisciplinary Exploration and Research in Astrophysics at Northwestern University. Kalogera was a lead author on a journal article on the neutron star collision co-authored by close to 4,000 scientists. We’ll also hear from physicist Mike Landry. He’s Head of LIGO Hanford — one of the sites that, in collaboration with Italy’s VIRGO detector, measured the neutron stars’ characteristic gravitational waves. 
 Orbital Path is produced by David Schulman. The program is edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Dr. Michelle Thaller. Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance. More at sloan.org Image credit: CALTECH/NSF/LIGO Sonoma State University/A. Simonnet Neutron star audio chirp credit: LIGO/University of Oregon/Ben Farr

Scientists in 1985 discovered something that threatened the world we live in: The ozone layer had a hole in it. A big one. And this hole was growing very quickly. If it continued to grow, the consequences would be dire. Presented with the science, world leaders came up with an international agreement. The Montreal Protocol, as the treaty was called, may elicit shrugs today. But it staved off disaster for Earth. It was a remarkable success story, and our planet today would be a very different place if not for the Montreal Protocol and the so-called “blue sky” scientific research — research for curiosity’s sake — that led to the discovery of the rapid deterioration of the ozone layer, and its causes In this episode, we return to a program originally broadcast in January 2017 — one that is perhaps even more relevant today. Orbital Path is from PRX and produced by David Schulman. Justin O’Neill produced this episode. Orbital Path is edited by Andrea Mustain, with production oversight by John Barth and Genevieve Sponsler. Hosted by Dr. Michelle Thaller. Support for Orbital Path is provided by the Alfred P. Sloan Foundation, enhancing public understanding of science, technology, and economic performance.

In this darkest season of the year, Dr. Michelle Thaller and NASA astronomer Andrew Booth curl up by the fire. Gazing into the embers, red wine in hand, they consider the meaning of the winter solstice — on other planets. Like Uranus, where parts of the planet go 42 earth years without seeing the sun. Or Mars, where winters are made colder by an orbit politely described as “eccentric.” Or Saturn — where winter’s chill is deepened by the shadow of the planet’s luminous rings.  Marshmallow, anyone? 
Orbital Path is produced by David Schulman. The program is edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Dr. Michelle Thaller. Photo credit: NASA

NASA’S office of planetary defense isn’t worried about Klingons or Amoeboid Zingatularians.  They worry about asteroids and comets.  Like the one that exploded over Chelyabinsk, Russia in 2013. It was about 20 yards across. An asteroid 150 yards in diameter could take out a city. An even bigger one — as the dinosaurs reading this will attest — could change earth’s ecology, and lead to mass extinctions. Kelly Fast, program manager for NASA’s office of planetary defense, tells Dr. Michelle Thaller about an asteroid that watchers in Hawaii recently sighted:  a mysterious, massive, cigar-shaped object.  Millions of years into its journey, it was traveling faster than any spacecraft ever built by humans. It’s the first object ever known to visit our solar system that originated in the orbit of another star. Too fast to be trapped by our sun’s gravity, it’s now traveling a path that will take it back into deep, interstellar space. 

Orbital Path is produced by David Schulman. The program is edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Dr. Michelle Thaller.

 Illustration credit: ESO/M. Kornmesser

These days, astrophysicists like Dr. Michelle Thaller use instruments to probe the distant reaches of our galaxy, and far beyond. They use interferometry, the Hubble space telescope, and other technology impossible to imagine when the constellations of the winter sky were named. But, as the season changes and Orion returns to view, Michelle still finds plenty of wonder left for us to see — even with the naked eye — in the cold, clear air of a winter’s night.

 Orbital Path is produced by David Schulman (who returns this episode to answer Michelle’s questions about his recent alleged alien abduction). The program is edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Michelle Thaller.

 Photo credit: abductee# 29JE0391-RL-4S

We’ve got some awkward news to share, folks: The producer of Orbital Path is claiming he’s been abducted by space aliens. So this week, we’re dusting off the theremin and returning to one of our favorite early episodes — “Must Be Aliens.” Dr. Michelle Thaller talks with Phil Plait — AKA the “Bad Astronomer” — about the Kepler mission to find planets circling other stars … and why we humans are so quick to ascribe the unknowns of the cosmos to aliens. In the two years since this episode was originally produced, however, the universe has not stood still. So Michelle has an update on the Kepler project — and a discovery that, once upon a time, had certain astronomers murmuring the “A” word. Orbital Path is produced by David Schulman and edited by Andrea Mustain. “Must be Aliens” episode produced by Lauren Ober. Production oversight by John Barth and Genevieve Sponsler. Hosted by Michelle Thaller.

The Himalayan kingdom of Bhutan avidly guards its traditional culture. Bhutan is a nation that — instead of looking to GDP or debt ratios — measures success by an index of “Gross National Happiness.” In this episode of Orbital Path, Dr. Michelle Thaller describes her recent adventures in Bhutan — including a climb to a Buddhist monastery perched on the face of a cliff. In that rarefied air, Michelle was confronted by a link between the thinking of contemporary astrophysicists and old-school Bhutanese monks: a challenging concept of Time. 
Orbital Path is produced by David Schulman and edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Michelle Thaller.
 Photo credit: Michelle Thaller

We live our lives in three dimensions. But we also walk those three dimensions along a fourth dimension: time.

 Our world makes sense thanks to mathematics. Math lets us count our livestock, it lets us navigate our journeys. Mathematics has also proved an uncanny, stunningly accurate guide to what Brian Greene calls “the dark corners of reality.” 

But what happens when math takes us far, far beyond what we — as humans — are equipped to perceive with our senses?  What does it mean when mathematics tells us, in no uncertain terms, that the world exists not in three, not in four — but in no fewer than eleven dimensions? 

In this episode of Orbital Path, Brian Greene, director of Columbia’s Center for Theoretical Physics and a celebrated explainer of how our universe operates, sits down to talk with Dr. Michelle Thaller. Together they dig into the question of how we — as three-dimensional creatures — can come to terms with all those extra dimensions all around us.  
Orbital Path is produced by David Schulman and edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Michelle Thaller.

 Photo credit: World Science Festival / Greg Kessler.

 For more, visit briangreene.org

In a scary time, in a scary world, in a scary universe, NASA astronomer Andrew Booth says one of the things that frightens him most is math. Specifically, the power of mathematics to describe the universe. That’s because, beyond the comforting world of Newtonian physics, math gets mind-bendingly weird. So from the relative safety of their backyard hot tub, Dr. Michelle Thaller and Booth (who happen to be married) try to sort out what it really means to live not in just three dimensions, but in eleven — as mathematics now tells us we do. Join us in the hot tub as we turn on the jets, get wet, and weird…and just a little freaked out. Orbital Path is produced by David Schulman and edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Michelle Thaller. Photo: To see Michelle and Andrew in hot tub please use dimension 5.

Locked up on the Greek island of Crete, Icarus and his dad made wings out of  beeswax and bird feathers. They soared to freedom — but Icarus got cocky, flew too close to the sun, and fell into the sea.  A few thousand years later, NASA is ready to do the job right. The Parker Solar Probe is scheduled to fly in 2018. The spacecraft has a giant heat shield, tested to withstand 2,500-degree temperatures. For something so basic to all of our lives — and fundamental to the science of astronomy — the sun remains surprisingly mysterious. To learn more, Michelle meets up with Nicky Viall, a NASA heliophysicist working on the mission. She describes how direct measurements of the sun’s super-hot plasma, and solar wind, may dramatically enhance our understanding of the star at the center of our lives.

 Orbital Path is produced by David Schulman and edited by Andrea Mustain. Production oversight by John Barth and Genevieve Sponsler. Hosted by Michelle Thaller. Photo credit: NASA