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EarthDate

Switch Energy Alliance

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.

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  • 25 episodes
  • weekly
  • Avg 2 min
  • English

Episodes 25

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  • June 29 · 2 min

    Lakes of Life

    Charles Darwin proposed that life on Earth may have started in bodies of highly alkaline water called soda lakes. New research suggests he may have been right. You might remember from a prior EarthDate that phosphorus is an essential building block for DNA, RNA, and the energy carrier for cells, ATP. Without phosphorus, there is no life. Soda lakes are some of the few places on Earth where phosphorus is readily available, rather than bound up in rocks. Nearly all these lakes around the world are closed basins. Water enters, but there is no outlet. As rivers flow toward a soda lake, running water leaches minerals out of the rocks it passes over, notably calcium and phosphorus. These then concentrate in the lake. Normally, phosphorus would bond with dissolved carbonate compounds in the lake water and sink out. But calcium bonds more readily with carbonate than phosphorus, leaving the phosphorus in a pure form. Evaporation further concentrates it. In small soda lakes, the level of phosphorus rises and falls with the rains, and the amount of river inflow. But new studies on larger closed basins show that phosphorous concentrations can remain high year-round, indefinitely…

  • June 29 · 2 min

    Light Speed Under the Sea

    In 1858, Queen Victoria sent a telegraph to U.S. President Buchanan, via the first undersea cable. The cable worked for just a few weeks, but it launched an international cable network that still dominates global communication. We think we live in a wireless world. But it’s just the short hop from our phones and wifi to a receiving antenna. Nearly everything after that is transmitted by cable, on land and undersea. Undersea cables made of copper served the world for more than a hundred years. Then, in 1988, the first fiber-optic cable was laid. They’re made of strands of ultrapure glass, no thicker than a human hair. Hundreds of strands are bundled together and protected by braided metal and nylon, jacketed in plastic. At one end, electrical signals are converted to light by a laser, then shot down the fiber-optic cable, sometimes more than a thousand miles, between countries and continents. In the shallows, they’re buried in trenches to protect them. In deep water, they’re simply laid on the seabed, which is less expensive, but exposes them to harm. There are now thousands of subsea fiber-optic cables, stretching almost 1 million total miles, transmitting 95% of international internet and voice traffic. And more cables are being laid each year. So next time you make an international call, pause for a moment to imagine your voice rocketing along at the speed of light, under the sea.

  • June 28 · 2 min

    The Moth with Two Maps

    The giant bogong moth has a brain one-tenth the size of a grain of rice. And eyes the diameter of a human hair. Yet it can navigate by sensing the magnetic field of Earth. Or by gazing at the stars, reading a mental map that it was somehow born with. Each spring in Australia, they leave the lowlands by the millions, and fly at night over terrain they’ve never seen before, following their internal compass, and that inherited star map. They’re the only insects we know of that can navigate this way. And they’re all headed to the same place: the cool highlands of the Snowy Mountains, where they sleep away the summer heat in caves. Historically, they’ve been a keystone species here, with a disproportionately large effect on the ecosystem. Other animal populations have relied on their annual arrival for food. Aboriginal tribes used to gather in the mountains to harvest and roast moths. But the bogong has declined precipitously over the last decade. Rising temperatures and drought have reduced their food sources. Pesticides have reduced their numbers. Light pollution from towns and farms has reduced their ability to navigate. Conservation groups are trying to save the moth, but with so many stressors on their population, that’s hard to do. Let’s hope they’re successful, because the bogong moth is another overlooked example of the wonders of nature, its interconnectedness, and its vulnerability.

  • June 28 · 2 min

    The Crystal Eye of Ninevek

    During World War 2, an American pilot flying over the Canadian arctic saw something extraordinary. A midnight blue lake, 2 miles across, shaped in a perfect circle. The Allies kept it a secret, using the lake as a navigation landmark during the war. But in 1950, photos hit the media, and the lake became a sensation…because it shouldn’t exist. There were no rivers leading into it, and none leading out. There was not enough liquid groundwater in this frozen landscape to fill it. It was as if the lake had been dropped from the sky. And in fact, it had. Scientists soon determined it was formed by a huge meteorite. Its trajectory would have been straight down, striking Earth at 30,000 miles an hour, with the force of 8,000 Hiroshima bombs. It bored a hole more than 800 feet deep, and pushed up 500-foot high ridges around it, isolating it. Of course, the natives had known of the crater for centuries, calling it the Crystal Eye of Nunavik -- because it contains some of the clearest surface water on Earth. Research confirmed that the water came from melting Ice Age glaciers and is only recharged by melting snow and ice. With no rivers to bring in sediment, the soils on the lake bottom contain mostly dust, pollen and diatoms -- from millennia ago, preserved in the frigid water. In this way, the Crystal Eye literally lets scientists “see” into the distant past.

  • June 28 · 2 min

    We Changed Horses

    Horses changed human history. But first we had to change horses. The horse evolved in North America 50 million years ago, and migrated across the Bering land bridge into Eurasia. Then, during the last Ice Age, it went extinct in the Americas. Around 5,000 years ago, humans began taming horses in the Eurasian Steppe, in what is today Kazakhstan, Russia and Ukraine. There, archaeologists have found residue of mare’s milk in drinking vessels. Some horse skeletons show wear on their teeth suggesting they held bits in their mouth. But other skeletons have arrow points embedded in bones, suggesting that horses were hunted as much as domesticated. A thousand years later, a different steppe culture tamed a different horse and, evidence shows, developed a horse culture – so successfully that it replaced the earlier horses. Genetic testing revealed that this first domesticated breed, called DOM2, became the progenitor of all later horse breeds. With them, humans could travel farther and faster than ever before. Mounted nomads could cover landscapes. Mounted cavalry could vanquish enemies. Horses could pull carts, and later, plows. We hardly think about it today, but from 4,000 to just 100 years ago, horses were the driving force in human transportation, settlement and warfare. The only thing that moved more people was our own two feet.

Showing 21–25 of 25 episodes