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EarthDate: Daily Summaries Delivered
by 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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- 2 days ago2 min
Urban Bats
Forty years ago, bridge renovations in Austin, Texas attracted an unwelcome visitor – in fact over a million of them.Engineers had run support beams under the entire length of the bridge. Small slits between the beams opened into deep crevices …Just like those preferred by the Mexican freetail bat in their native habitat. Soon a huge colony lived under the bridge.And many Austin residents wanted them out. They had heard horror stories – bats spread disease! They might bite us!But Merlin Tuttle, a bat ecologist, knew they were not only harmless, but beneficial.Mexican freetails are insect eaters. Each evening this colony consumed more than 10 tons of mosquitoes and agricultural pests.The bats not only made Austin evenings more pleasant. They saved farmers downriver billions of dollars in crop losses and pesticides.Tuttle took live bats to show journalists, business leaders and schools – who largely found them adorable. He explained how they were good neighbors.Opinion began to change…and more visitors came. Humans this time, wanting to see the bats.Which brought two more benefits: tourism revenue, and civic pride -- of having the world’s largest urban bat colony.
- 1 weeks ago2 min
Importing Trash
In America, we’re number one! In many things. Some are not so good. Like garbage. Each American makes 1500 pounds of it a year.Two-thirds could be recycled, but isn’t. Most goes to landfills.Who’s number one in recycling? Sweden. Just 1% of their garbage is landfilled.In the 80s, Sweden began building a circular economy for garbage. They tasked manufacturers to devise ways to handle their packaging after it was used.And they created robust consumer recycling programs and education. Now half their waste is reused or recycled.The other half goes to incinerators. They burn that garbage to make electricity, and the hot wastewater is pumped to houses to heat them.In this way, they supply 15% of Sweden’s power and 10% of its heat.Yet, incineration isn’t perfect. It produces emissions, like CO2 and other gases. Sweden’s plants capture most of them.And to keep its incinerators running, Sweden now needs more garbage than it makes – so they import it -- from other EU countries for a fee. Then recycle some and burn the rest.Could the US reduce our garbage streams like Sweden? They’re a tiny country, a third the size of Texas. And the U.S. has different regulations in all 50 states.Still, we could do much better with recycling and economic reuse. And every year there are more programs to help us do just that.
- 2 weeks ago2 min
Where Did I Put That Acorn?
Have you ever wondered how squirrels find the nuts they hid months before?A typical squirrel can store 3,000 of them in a fall season, in dozens of locations. It seems almost impossible that they could remember them. But they do.There are 200 species of ground squirrel, tree squirrel and flying squirrel that rely on stored seeds and nuts.To do that, they need to return to them even after leaves fall and snow covers the ground. How do they do it?Smell plays a role. But sight and memory are more important.Squirrels build a mental map of their surroundings: a tree trunk, a large rock, a fallen log, a fence post.Then they remember the changing spatial relationships between those landmarks when viewed from their different food hiding places.Some scientists have wondered if a squirrel’s brain grows to meet the season’s mental demands.Because there are other rodents -- shrews, European moles and weasels – whose brains contract 10% in winter when food is scarce, then expand again in spring, with no impact on function.But most research suggests a squirrel’s heightened spatial memory is linked to its larger than normal hippocampus, a part of the brain involved in learning and navigation.They’ve also shown more neuron growth, and less age-related mental decline.To fuel this acuity, squirrels require a lot of calories – which ironically means they must hide more nuts to help them find the others!
- 3 weeks ago2 min
Lighting More With Less
LEDs are everywhere today. But what does L. E. D. stand for anyway?Luminous Efficiency Device? Less Electricity Demanded?Not quite – though both correctly describe Light Emitting Diodes. They make more light, from less electricity, than any other technology.Incandescent bulbs of the 20th century heat a metal filament until it glows white hot. They produce light, but much more electricity is converted into, and wasted as, heat.Fluorescent tubes pass energy through a gas that glows. They consume less electricity, but their light is not so attractive, they must be disposed of properly, and the bulbs can be fragile.So scientists kept pushing for something better, and invented LEDs in the 1960s. The initial technology was basic and expensive, but worked the same way it does today:Electricity flows through a two-layered semiconductor. One layer has an excess of negatively charged electrons.The electricity forces electrons to jump to the other positively charged layer to equalize. As they do, they release a small amount of energy as light.Multiply that over millions of electrons and these diodes can emit a great deal of light, with very little energy wasted as heat.They’re such a step up over old bulbs, that LEDs now make up half of global lighting, and growing.
- Sep 29, 20262 min
Where Rust Shouldn't Be
Rust is common on Earth. It shouldn’t exist on the moon. But somehow, it does.Rust is just the common name for iron oxide. Iron that has bonded to oxygen.The moon, however, has no oxygen. Yet lunar rovers have recovered grains of iron oxide in lunar soil. How could they have gotten there?One possibility is from Earth. Or rather, from our atmosphere.The magnetic field of our planet, called its magnetosphere, surrounds Earth like an invisible force field.The sun produces a solar wind of charged particles that flows outward into the solar system.When it encounters our magnetosphere, it deflects around Earth. The charged particles flow around us and deep into space, in a so-called magnetotail that stretches three million miles behind Earth.As the charged particles pass, they strip off some oxygen ions from the upper reaches of our atmosphere, and carry them into the long magnetotail.Each month during the full moon, Earth is between the moon and the Sun, which may shelter the moon from solar wind, and bathe it in oxygen from Earth’s magnetotail.Scientists believe that when these oxygen ions strike the moon’s surface, they bond with iron in the lunar soil to form, yes, tiny particles of rust.This is still a hypothesis. But it’s important because it highlights how little we know about our closest celestial neighbor… where humans might soon spend a bit more time.
- Sep 22, 20262 min
Sole Survivors
Imagine there was not one species of human…but many. One stronger. One smaller. All different, but closely related.Around 40,000 years ago, that’s exactly how it was. Homo sapiens – us – shared Earth with several other Homo species. Then those other ones went extinct, and we carried on. The sole survivors.Why? Because we could better adapt to changing climates. And that’s because of a few key qualities.First, we had more flexible diets. We could eat large animals or small. Fish, fowl, or foraged plants.One reason we could do that, is we also had better control of fire. Which allowed us to cook those various foods to extract more nutrients and calories.We also had better tools, to more effectively butcher animals, and importantly, sew their hides into fitted clothing and covering for shelters -- which allowed us to endure the bitter cold of the Ice Age.And because of those things, we were mobile. We could take our tools, clothing and shelters, flexible diets and fire to cook them, to different regions as climate patterns changed.We also had dogs, for hunting. And to hear that amazing story, look it up on EarthDate.org.But there’s one more Homo sapiens trait that may have mattered most of all. We had advanced language, to communicate the knowledge of all these things, to cooperate and collaborate, and to build the social cohesion required to weather difficult environments.
- Sep 15, 20262 min
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.
- Sep 8, 20262 min
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!
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About EarthDate
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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