Podcast
EarthDate
Hosted by Switch Energy Alliance · EN
EarthDate is a short-format weekly audio program delivering concise, science-based stories about the Earth: its geology, environments, and the processes that shape our planet over deep time and today. Beginning in 2026, EarthDate is managed by Switch Energy Alliance and hosted by SEA's founder Dr. Scott W. Tinker. Together, we explore earth systems, natural resources, and their relevance to everyday life, with a focus on clear, accessible science education for broad audiences. EarthDate is written and directed by Emmy-winning filmmaker Harry Lynch, and researched by Lynn Kistler. We search for captivating stories to remind listeners that science can enlighten, educate and entertain.
129episodes
Episodes
Newest firstAll episodes
Mount St. Helens Eruption
Jun 1300:02:00Tap to summarizeThe blast was over a thousand times stronger than Hiroshima, heard 700 miles away. It killed 57 people and countless animals.This was the eruption of Mount St. Helens 45 years ago in Washington, the deadliest, most damaging volcanic event in modern US history.Surprisingly, in America today there are 169 active volcanoes. Most are in Alaska. A few in Hawaii have small eruptions regularly.There are 20 volcanoes in Washington and Oregon, where the Juan de Fuca tectonic plate subducts under North America, melting as it’s pushed down into Earth’s mantle, and rising to produce volcanoes at the surface.A few are active, but St. Helen’s is different. It’s 25 miles west of the others, where the tectonic subduction zone is 20 miles nearer the surface.In 1980, magma blasted sideways through a mile long gash on the side of the mountain. on the side of the mountain, flattening trees in an 8-mile radius. Pyroclastic flows set forest fires. Mudslides filled lakes and diverted rivers, causing massive floods.But within weeks, fireweed sprouted from roots. Lupine and huckleberry crept across the landscape. Insects, burrowing animals and elk soon returned. Aquatic ecosystems rebounded.Today, the top of the peak is gone, replaced by a huge caldera. But new trees have grown tall and the forest has returned.
Transcribe →Martian Meteorites
Jun 1300:02:00Tap to summarizeSometime long ago, a small meteorite crashed into the sands of the Sahara. In 2011, scientists discovered it and dubbed it NWA 7034 – nickname: Black Beauty. It was soon recognized as the rarest meteorite on Earth.Black Beauty came from Mars. Scientists know that because oxygen isotopes trapped within it match those in the Martian atmosphere.Because that atmosphere is so thin, Mars is not well protected from asteroids. When they impact the surface, they explode off chunks of rock. Some of these travel out into space, where they drift for years, before becoming trapped in Earth’s stronger gravity field, and pulled to us.Most burn up as they rocket through our much thicker atmosphere. We’ve only recovered 74,000 meteorites worldwide that have made it to Earth’s surface.The large majority are fragments of asteroids; less than 400 are from Mars. And of those, there is only one Black Beauty.That’s because it’s brecciated, meaning made up of tiny chunks of many different rocks from the surface of Mars, that have been accreted together over time.Geologists can study how the breccia formed and ‘read’ each of the small fragments within it to interpret their origins, and better understand the geology of Mars.That makes Black Beauty, though just the size of a tennis ball, the most studied meteorite on Earth.
Transcribe →Mystery of the Wallace Line
Jun 1200:02:00Tap to summarizeThe Wallace Line, a boundary separating the unique species of Australia from those of Southeast Asia, has long fascinated scientists. Exploring the influence of plate tectonics, glacial periods, and geographic isolation may hold the answer to this mystery.
Transcribe →Wildfires Impact Snowpack
Jun 1200:02:00Tap to summarizeSnowpack provides our water, especially in the American West. And new research shows wildfires may be affecting it.Snow accumulates in the mountains in winter, then melts in spring to fill rivers. As we’ve discussed in prior EarthDates, that runoff is critical to water supplies, for irrigation, fisheries and cities.Earlier melting, due to more winter rain, has brought spring floods. This can mean lower water supplies in summer and fall. Now wildfires have been shown to also promote earlier melting.For the past century, U.S. forestry policy has been to put out all wildfires, which has led to an accumulation of deadwood that could burn as fuel.Combine this with hot, dry “fire weather,” and more people now living in fire zones, who set more fires, and the result is more acres of Western forests burned each year.Scientists analyzing snowpack across Western mountains found that an evergreen forest canopy reduces the amount of snow that can accumulate on the ground. But it reflects more sunlight from snow-covered branches. This keeps the ground cooler and slows melting.By contrast, where a forest has burned, more snow accumulates on the ground. But it reflects less sunlight, warms faster and melts as much as 10 days earlier in the season.More research is needed to understand how earlier melting in burned areas may affect runoff. But it could be another important tool for scientists analyzing water supplies in a parched American West.
Transcribe →The Birth… of Earth
May 3100:02:00Tap to summarizeIn the beginning, Earth was hell.The planet was completely molten, a roiling sea of magma at temperatures of thousands of degrees. Scientists even referenced Hades to name this period: Hadean Earth.How did it become the green paradise we know today? Well, over about half a billion years, it cooled. And how it cooled has shaped some important traits of Earth to this day. Logically then, scientists are studying what happened.They use seismic waves from natural earthquakes and man-made explosions to map today’s inner Earth. And they’re using theoretical modeling to study its ancient past, which suggests that Earth cooled like this:Very hot surface material, in contact with an early atmosphere, began to cool first.Convection currents carried warmer magma from Earth’s center up toward the surface and forced cooler material back down.Metals and elements attracted to iron sunk out of the current to form a central iron and nickel core.The mantle between surface and core began to cool next, while the lowermost mantle remained liquid.Scientists think this basal magma ocean had strong fluid currents within it, which may have converted kinetic energy into electromagnetic energy. This could have helped start Earth’s geodynamo—which today generates Earth’s magnetic field from its metal core.But as with all science, this research is ongoing—so expect updates on a future EarthDate.
Transcribe →Shark Planet
May 3100:02:00Tap to summarizeSharks have been so successful, for so much longer than so many other lifeforms, that you could call Earth the shark planet.They evolved over 400 million years ago, meaning they’re older than trees. They’re 6 times older than the North Star! And over a thousand times older than humans. They’ve survived all 5 known mass extinction events.Over that long, long period, they’ve diverged into hundreds of species and adapted to every marine environment from deep oceans to estuaries.And they’re magnificent creatures: sharks recover from injury and heal quickly. They almost never develop cancers or get heart disease. And they’re immune to infections. Some species, like the Greenland shark, can live more than 400 years.Sharks are essential to the health of Earth’s oceans, culling sick and weak fish and scavenging dead ones. But today, they’re in great danger.Sharks mature and reproduce slowly, so they don’t adapt quickly to environmental changes.While they’re highly efficient predators, they have almost no interest in humans—we’re not their natural prey.But they’re often killed by fishermen. And their numbers are declining from overfishing, mostly for shark fin soup. Eighty million are caught each year, often their fins cut off while alive, then they’re thrown back to die.Instead of killing them, we should admire and protect one of Earth’s oldest and most well-adapted animals.
Transcribe →Pompeii: The Destruction
May 3100:02:00Tap to summarizeFor millennia, people have been drawn to volcanoes.Why? Because before they arrived, the volcanoes had erupted.Their lava, ash and debris covered the surrounding area, making for fertile farmlands that drew settlers … who may not have recognized that the volcanoes could erupt again.And that’s just what happened around Italy’s Mount Vesuvius. Long before the Romans, people had come to farm there. When Rome eventually controlled the region, inspired by the pleasant climate and bountiful agriculture, they named it Campania Felix—the happy, fertile countryside.One of the happiest towns was Pompeii, a popular vacation spot of the day. But Mount Vesuvius would change all that.In AD 62, it sent earthquakes through the region, displacing residents. Most had returned when, 17 years later, Vesuvius erupted.First, it blasted a spire of ash and pumice 10 miles into the sky. This rained down on Pompeii, leaving a layer 8 feet thick. Most citizens fled, but 2,000 remained, sheltering in stone houses and cellars.The next day, clouds of burning hot toxic gas flowed down the mountain, instantly suffocating residents. More ash rained down, encasing the victims in their final positions.Their tragic end, however, would be a great boon to historians centuries later – which we’ll discuss in the next EarthDate.
Transcribe →Mammoth Cave’s Rich History
May 3100:02:00Tap to summarizeIn 1797, in central Kentucky, a hunter chased a bear into a hole in a cliff … and discovered the longest cave network in the world, 10 million years in the making.But at that time, all he could see—and smell—was bat guano, which was then the valuable source of saltpeter, a key component in gunpowder.Within a year, prospectors were mining centuries of bat droppings for military efforts. During the War of 1812, the gunpowder business boomed, and so did the cave’s mine. In 1815 the war ended, and so did the mine.The next year, Mammoth Cave, named for its enormous size, opened as a tourist attraction. The slaves who had been the miners now served as tour guides.They showed the cave to Gilded Age patrons, who carried oil lamps and used their smoke to write their names on the ceiling.In the 1840s, a freed slave named Stephen Bishop, an expert cave guide, was the first to explore and map the cave.After a century of tourism, it was thought to comprise more than 40 miles of caverns and connected passages.But new scientific exploration and technology, continuing to the present day, has revealed it’s actually 10 times that size. And more rooms are expected to be found.Today, the cave’s petroglyphs and speleothem formations are seen by half a million visitors a year. If you find yourself in Kentucky, be one of them!
Transcribe →Deep Ocean Drilling
May 3100:02:00Tap to summarizeFor nearly 60 years, an international deep ocean drilling program has revolutionized earth science and understanding.Two research ships in particular, the Glomar Challenger, later replaced by the JOIDES Resolution, have drilled hundreds of miles of ocean sediment core, in every ocean. These cores provide a record of Earth stretching back millions of years.They’ve allowed scientists to validate the theory of plate tectonics, study ancient sea creatures, climate and sea level fluctuations, past earthquakes, volcanoes, asteroid impacts, changes in Earth’s magnetic field and more.And they’ve furthered science in monumental ways. They’ve helped us build the geologic time scale. Make the link between natural orbital cycles and long-term climate variability. Map global ocean circulation patterns to better understand how they warm continents and influence weather.They’ve shown us that the Mediterranean Sea has completely dried out, several times, and that the Arctic was once subtropical, abounding with warm-water life forms.They’ve discovered frozen natural gas beneath the seafloor, along with the sunken continent of Zealandia.In September 2024, the Resolution will be retired, after almost 40 years of service. Smaller European and Japanese ships will keep on drilling, while hopefully the U.S. builds another flagship, to continue the scientific discovery vital to human progress.
Transcribe →Plants Can Dance
May 3100:02:00Tap to summarizeYou might think that plants are stationary, but did you know they can dance?Many flowers do a daily sun dance, swinging from east to west, to produce more pollen and attract insect pollinators.They make this movement using two methods:Plants contain a compound called phototropin that responds to being in shadow by causing cells to elongate. In this way, the dark side of the plant grows longer, which curves the other slower-growing side toward the light.All plants do this, but the sunflower is special. It can elongate its cells every minute!Each day as the Sun moves westward, cells on the east side of the stem just beneath the flower grow, tilting the flowerhead westward to follow the Sun. At night, the west side grows, pushing the flower back toward the east to greet the morning sun.The sunflower will do this daily dance until fully mature, when it stops growing, usually with the head facing east.Other plants in the sunflower family, like daisies and dandelions, can also follow the Sun, but use a different method. They pump potassium and water across cell membranes to inflate or deflate cells, thereby bending the stem.Using these methods, many plants can change their orientation, not only to light, but moisture, gravity and other stimuli.Not exactly dancing, but moving in rhythm more than we might think.
Transcribe →