pplpod

In 13,000 years Polaris will no longer mark true north, because Earth is not a perfectly spinning top. This episode unpacks the three orbital rhythms that Serbian geophysicist Milutin Milankovitch calculated by hand in the 1920s: eccentricity, the stretching of Earth's orbit on roughly 100,000 and 400,000 year timescales that can change incoming solar radiation by up to 23 percent; obliquity, the...

Chris Hadfield went blind during a spacewalk while moving at 17,000 miles per hour, and his response was to work the problem. This episode traces how a kid from a corn farm in southern Ontario, inspired by the 1969 Apollo 11 broadcast at age nine, systematically built himself into someone a space agency could not ignore: air cadet glider scholarships, a mechanical engineering degree from the Royal...

Black holes were once thought to be perfect cosmic prisons, but Stephen Hawking's math showed they slowly leak energy and eventually evaporate. This episode traces how that idea emerged: Jacob Bekenstein's 1972 claim that black holes carry entropy proportional to their surface area, Hawking's attempt to disprove it, his 1973 Moscow meeting with Zeldovich and Starobinsky, and the equations that end...

In 1581 a bored medical student in Pisa Cathedral timed a swinging chandelier against his own pulse and discovered that a pendulum's period does not depend on the width of its swing. This deep dive moves past the cardboard cutout of Galileo Galilei to reveal a financially stressed, artistically trained Renaissance man. It covers his father Vincenzo's lute string experiments linking tension to pitc...

At the end of the chaotic year 1968, an anonymous telegram told three men that they had saved it. This deep dive tells the story of Apollo 8 and Frank Borman, Jim Lovell, and William Anders, beginning with a lunar module that arrived with over a hundred defects, the Soviet Zond 5 flight that sent tortoises around the Moon, and the N-1 rocket spotted on a launch pad. Those pressures led George Low...

Billions of miles beyond Neptune spins a world so fast it has stretched itself into the shape of a squashed football. This deep dive explores Haumea, the dwarf planet nicknamed Santa when it was spotted around the holidays, the third largest known trans-Neptunian object after Eris and Pluto, and the fastest rotating equilibrium body in the solar system with a 3.9-hour day. The episode explains how...

Mark Twain was born in 1835 as Halley's Comet blazed overhead and predicted he would go out with it; he died in 1910 on its return. This deep dive uses that story to frame the comet as an icy metronome for human history, tracing it from Han Dynasty Chinese records in 240 BC through Rome in 12 BC, the Bayeux Tapestry and the Battle of Hastings in 1066, the founding of Debre Berhan in Ethiopia in 14...

Guion Stewart Bluford Jr. holds a resume that reads like a science fiction character sheet: aerospace engineering PhD with a minor in laser physics, 144 combat missions over Vietnam in the F-4C Phantom, more than 5,200 hours in high-performance jets, and 688 hours in space. This deep dive looks past the headline that he was the first African American in space to examine why NASA came to treat him...

In 1301 the painter Giotto di Bondone saw a comet so striking he later painted it as the Star of Bethlehem. Nearly seven centuries later the European Space Agency named a spacecraft after him and sent it straight into that same comet. This deep dive covers the turbulent birth of the Giotto mission after NASA pulled out of the joint International Comet Mission in 1979, the rejected HAPPEN proposal,...

Ganymede is wider than Mercury, holds more liquid water than all of Earth's oceans combined, and is the only moon in the solar system that generates its own magnetic field. This deep dive explores why Jupiter's largest satellite acts like a fully fledged planet. It begins with the 1610 discoveries by Galileo and Simon Marius, the puzzling 365 BC Chinese record of astronomer Gan De seeing a reddish...

A day-old corned beef sandwich smuggled aboard Gemini 3 in 1965 triggered a congressional inquiry over floating breadcrumbs. This deep dive uses that famous incident as a gateway into the surprisingly high-stakes science of eating in orbit. It starts with the Mercury-era fear that humans could not swallow without gravity, the gelatin-coated cubes and toothpaste tubes that resulted, Yuri Gagarin's...

The first artificial object to reach space was a Nazi weapon of war, and the man who designed it later became chief architect of the rocket that carried Americans to the Moon. This deep dive confronts the dual legacy of Wernher von Braun, from his Prussian aristocratic childhood, cello lessons, and a confirmation-gift telescope to the Hermann Oberth book that forced a math-averse teenager to maste...

On August 6, 2013, a car-sized robot alone on Mars hummed Happy Birthday to itself to mark one Earth year on the surface. This deep dive tells the biographical story of NASA's Curiosity rover, launched in 2011 with a two-year primary mission and still operating in 2026. It covers the nearly three-meter, 900-kilogram chassis, the multi-mission radioisotope thermoelectric generator fueled by 4.8 kil...

In 1917, astronomer Walter Sydney Adams noted a strange smudge in a white dwarf spectrum at Mount Wilson and filed the glass plate away. Ninety-nine years later, scientists realized it was the pulverized remains of an exoplanet being consumed by its star. This deep dive follows the long road from that overlooked plate through a century of false starts, including William Stephen Jacob's 1855 claim,...

Johannes Kepler flatly rejected the idea of planets orbiting other stars, so there is a certain irony in NASA naming a $600 million telescope after him in 2009 to prove him wrong. This deep dive explains how the Kepler Space Telescope used the transit method to watch roughly 150,000 stars for brightness dips of about 0.01 percent, why it needed a 1.4-meter ultra-low expansion mirror and a 94.6-meg...

Imagine looking up from your porch and seeing another town arching miles overhead, hanging upside down inside a colossal rotating tube. This deep dive explores the O'Neill Cylinder, a blueprint born in Gerard K. O'Neill's early 1970s Princeton physics class and formalized in his 1976 book The High Frontier. The episode walks through the three island reference designs, the twin counter-rotating cyl...

NASA's Europa Clipper is a $4.25 billion armored, solar-powered spacecraft carrying a poem by Ada Limon, the word water in 103 languages, and a microchip with 2.6 million names toward an ice-covered ocean moon. This deep dive unpacks the saga of getting it off the ground: the fight to move from the SLS to a SpaceX Falcon Heavy that saved an estimated $2 billion and avoided a $1 billion vibration r...

Most people know Edmond Halley only for the comet that bears his name, but this deep dive argues that is a massive historical injustice. Born in 1656 to a wealthy London soapmaker, Halley arrived at Oxford with a 24-foot telescope, corrected the Astronomer Royal's tables as a student, then abandoned his degree to sail to St. Helena and catalog 341 southern stars. There he observed a transit of Mer...

NASA's Viking program launched in 1975 with two orbiter-lander pairs, a roughly $1 billion budget (about $6 billion today), and one overriding goal: find life on Mars. This deep dive traces the full lifecycle of these machines, from plutonium-238 RTG power and 40-hour bioshield baking at 111 degrees Celsius to the parachute-then-freefall landing sequence with 18 purified-hydrazine nozzles designed...

Controlling a lander behind the moon is like flying a drone from behind a brick wall thousands of miles thick. This episode explains how the China National Space Administration's Chang'e 4 mission solved that radio blackout to make the first-ever soft landing on the lunar far side on January 3, 2019, inside the Von Karman crater within the South Pole-Aitken Basin, an impact scar roughly 13 kilomet...

Charles Messier spent his life obsessed with hunting comets, and history remembers him for the catalog of fuzzy objects he compiled so he could ignore them. This episode explores the 18th-century French astronomer's story, from a childhood in Lorraine marked by the death of six siblings and his father, to the Great Comet of 1744 and the 1748 annular eclipse that offered a grieving boy the reliable...

In 1939 a four-year-old boy at the New York World's Fair watched a time capsule being buried for a civilization thousands of years away. That boy grew up to send humanity's own time capsules into interstellar space. This episode traces Carl Sagan's worldview from a Depression-era Brooklyn childhood shaped by an analytical mother and an empathetic father, through the library book that revealed star...

Burn a secret diary and physics says a powerful enough computer could reconstruct every word from the ash and smoke. Drop that diary into a black hole and the answer becomes the black hole information paradox, a head-on collision between quantum mechanics and general relativity. This episode explains unitarity, why quantum evolution must be reversible, and how Stephen Hawking's 1970s calculation o...

The most famous photograph of a man on the moon almost certainly shows Buzz Aldrin, not Neil Armstrong, because NASA forgot to plan who would hold the camera. This episode goes inside that spacesuit to trace a fiercely independent life, from a New Jersey kid nicknamed by a sister who could not say brother, to the West Point cadet who defied his father's bomber plans, flew 66 combat missions in Kor...

For over half a century the moon has been a graveyard of 1970s hardware, but as of April 2026 four humans have looped around it again. This episode unpacks NASA's Artemis program as a multi-national, multi-generational effort to build a permanent lunar presence rather than repeat Apollo's camping trip, and how it survived from the cancelled Constellation program through three presidential administ...