EarthDate

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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.

  1. 21h ago

    Gold is Abundant

    Gold is rare. Except in one place on Earth that it’s incredibly plentiful. But we’ll probably never get to it. Over the course of human civilization, people have searched for gold. Still, we haven’t found much – 220,000 tons across all those centuries. By comparison, we’ve mined seven times as much silver. And 3,000 times more copper. But we now know there’s much, much more gold on Earth. When the planet formed, more than 4 billion years ago, many metals swirled together in Earth’s molten magma, gold among them. Being heavy, it was pulled toward the center, into Earth’s core, by the force of gravity. There it bonded with abundant iron. And there it has mostly stayed. But Earth’s interior is not static. The molten magma sometimes upwells toward the surface. Over millions of years these magma currents have carried small amounts of gold and other metals out of the core. Earthquakes and shifting tectonic plates then brought that magma toward the surface. Some of it precipitated out in veins, which we have mined. And some of that eroded into rivers and streams, and we gathered it there too. Because it’s valued, and doesn’t oxidize, most of the gold we’ve found over the years still exists in pure form and gold-rich alloys, and is still in use – in jewelry, art, electronics, even medicine. It may be precious, but it’s not scarce. It’s just that Earth has limited our access.

  2. Sep 8

    Life on Mars?

    Is there life on Mars? That’s the question NASA wanted its first Mars mission to answer – in 1976. They designed their remarkable Viking rover -- well before modern computers -- to collect and test soil samples, 140 million miles from Earth. First, Viking added a nutrient solution to the soil, looking for carbon dioxide that microbes would produce if they consumed it. And the test showed a small amount! Next, Viking incubated the sample to see if microbes, if present, could produce organic matter. A tiny amount was detected! But the third test would be conclusive. The rover incinerated the soil to gasify its compounds, then used a spectrometer to evaluate them. If there were organic matter, it would surely show up. But it didn’t. At the time, the answer was: no life on Mars. Several decades later, subsequent missions, using different tests, did find signs of microbial activity. So NASA went back to review the Viking data. With 50 years of new understanding, many scientists now believe that salt compounds in the Martian soil, when heated, would have destroyed any organic matter. Meaning Viking’s gas test may not have been designed or understood correctly. Today, there’s still no solid proof that Mars has microbial life. But new -- and half-century old -- tests haven’t ruled it out either!

  3. Sep 1

    Warm Springs for Winter Manatees

    A large manatee can top 1000 pounds and eat 15% of its weight in seagrass each day. That may sound hardy, but manatees are actually very sensitive. There are three species, all adapted only to the constant warm waters of the tropics. But the West Indian manatee has found a way to survive Florida winters by taking advantage of the state’s geology. As temperatures drop, manatees leave coastal waters and swim up rivers toward headwater springs. Florida has hundreds of springs, more than any other state, and some are huge, pumping out millions of gallons a day. The springs are fed by rainwater that percolates through Florida’s limestone bedrock, flows underground, is heated by geothermal energy, then emerges to form warm, clear pools that feed rivers. The spring pools are home to large ecosystems of many species -- including, in winter, manatees, who come by the hundreds to spend the cold months lounging, and eating. Like so many things in nature, the springs are under pressure from human development. Florida cities and agriculture pull water from the aquifer, reducing flow into the pools. Fertilizer seeps into the groundwater and enters the springs, clogging them with algae. Despite that, the manatees’ numbers are increasing, due to conservation efforts by Florida preservation groups. A success story of shared resource use that can hopefully sustain these remarkable creatures long into the future.

  4. Aug 25

    Mapping a Killer

    In the mid-1800s, London’s SoHo neighborhood was a terrible smelling place to live, as raw sewage ran through the gutters into open cesspools. When a cholera epidemic broke out, 600 people died and many remaining residents fled, fearing – as was common then – that foul air spread the disease. Local physician John Snow didn’t buy it. Ten years earlier, he had proposed that cholera spread through contaminated water. But lacking proof, he was ignored. With an outbreak on his doorstep, he saw an opportunity to test his hypothesis – and save his neighborhood. First, he obtained the addresses of every person who had died. Then he walked the streets plotting the deaths, and everything else, on a map. Soon a pattern emerged. Most of the cases clustered around one public water well. He began interviewing area residents. Locals with their own private wells had not gotten sick. Workers at a nearby pub, who drank a daily ration of beer instead of pump water, were also spared. Snow convinced local authorities that water from the well was to blame, and persuaded them to remove the pump handle, forcing residents to draw their water elsewhere. Immediately the cholera outbreak ended. With his cholera map, Snow had begun the field of evidence-based epidemiology. This was well before germ theory and microscopes could identify the true culprit, the cholera bacteria, that had spread through sewage leaking into the water supply.

  5. Aug 18

    Ocean Cleanup

    Plastic has remarkable value to humans. But it’s also a major source of ocean plastic pollution. Most of it is nets and rope from fishing boats, or municipal garbage that’s carried down rivers into the ocean. There it accumulates in spinning gyres of plastic, twice the size of Texas. Large pieces eventually break down into fragments and microplastics. But because plastic is made to be durable, it won’t degrade any farther than that. Wouldn’t it be great if we could clean it up? That’s what a Dutch teenager thought when he was diving in Greece and saw more plastic bags than fish. He created a high school science project -- that has since grown into an international nonprofit, called The Ocean Cleanup, employing engineers, marine biologists and collection teams. They set up huge U-shaped nets that float with the current in the spinning gyres, in the top few feet of water where most plastics (but few fish) are. These gradually capture the debris, which their boats collect and haul to shore. They’ve also installed collection systems at the mouths of rivers to intercept plastic before it enters the ocean. Together, their systems have captured millions of pounds of plastic waste, which they sort, recycle or properly landfill. There’s much more to do, but they’ve inspired governments and other nonprofits to work on plastic waste management on land and at sea. Hopefully, with growing awareness, we can all make a meaningful difference in ocean plastic pollution.

  6. Aug 11

    The Right Kind of Sand

    Sand is incredibly common. There are oceans of it – in oceans, and deserts too. But, for our purposes, that’s not the right kind of sand. We use sand in concrete, to make bridges and roads, buildings, houses and power plants. We use it in glassmaking, for windows, computer chips, solar panels and much more. We use it for hydraulic fracturing, to prop open cracks in shale deposits so oil and gas can flow. In all, we use billions of tons of sand every year. But only a certain kind will do. Beach sand is often mixed with salt. If used in concrete, it can corrode the reinforcing steel. And the grains of beach sand, and especially desert sand, are often rounded by waves or wind. Concrete needs angular grains that lock together. Hydraulic fracturing needs hard grains that can withstand pressure. And glassmaking needs almost pure quartz. That means, for most uses, the ideal sand is angular, well-sorted quartz. And that’s only found in a few places. Rivers and streams are natural sorting machines. They break down and wash out weaker minerals, leaving quartz sand in bars and banks, which can be dredged or mined. Through time, many of these quartz sand deposits were lithified into sandstone, which today can be ground back into sand. Our demand is so great that this once common material is becoming scarce, spawning a lucrative international trade -- for the right kind of sand.

  7. Aug 4

    Dangerous Downbursts

    In 1985, a passenger jet landing at DFW airport was forced to the ground by an unusual downward blast of wind called a downburst. The plane struck cars on the highway and a water tank, then crashed on the airfield, killing more than 100 people. It was the third such fatal crash in a decade. So, the FAA set out to invent a new warning system for these dangerous wind events. A downburst is a sinking column of air within a thunder cloud that accelerates toward Earth, reaching speeds over 100 miles an hour.  When it strikes the ground, it blasts out in all directions, like a mammoth version of water splashing in a sink. These winds are strongest just 10 to 30 feet from the ground and travel horizontally outward in all directions. They can fell trees like a tornado’s whirling winds, but they all fall in the same direction, like dominoes. For aviation, the first step was training pilots to look for visual signs – expanding rings of dust on the ground below, or sharply defined shafts of intense rain. Technologically things were more complex. Vulnerable airports installed a network of wind sensors, as well as advanced Doppler radar that could track wind speeds. All fed into an early alert system. By 1994, 46 high traffic airports had installed these systems. They haven’t had a single downburst accident since -- and technology continues to improve. A triumph of aviation safety.

  8. Aug 4

    Beating the Heat

    Before modern energy gave us modern air conditioning, we had sweat to keep us cool. And shade. And maybe a jump in a lake. Animals still rely on those today to beat the heat. Horses, like humans, sweat. When the sweat evaporates, it cools the skin. Dogs, antelopes and some birds pant, drawing breath rapidly across their tongues and throats, where evaporative cooling brings down the temperature of blood near the skin surface. Other birds vibrate the flaps of skin on their throats to circulate air around blood vessels found there. Elephants do something similar, cooling blood vessels in their huge ears, by flapping them. Camels and toucans draw air across blood vessels in their noses. Rodents and amphibians burrow in the soil or under leaf litter, where it’s cooler and moister. Some toads burrow and go dormant until the next rain comes. Some even form a protective cocoon of their own shed skin. Deer, doves and many other creatures seek shade during the heat of the day, resting silently to keep metabolic rates low. Even fish seek shade underwater, under overhanging rocks or docks. Or they retreat to the dark depths, where the water’s cooler. Speaking of water, buffalo and birds splash in shallow pools. Vultures, maybe not surprisingly, go so far as to pee on their own legs to cool themselves off. Which just goes to show, when the heat rises, animals have found amazing ways to adapt.

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About

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.

Information

  • Creator
    Switch Energy Alliance
  • Years Active
    2026
  • Episodes
    300
  • Rating
    Clean
  • Copyright
    © Copyright 2026 EarthDate
  • Show Website
    EarthDate