Episodes

You may have seen, years ago, commercials for cubic zirconia—a synthetic diamond substitute —and been unimpressed. But naturally occurring zircon crystals, made from zirconium silicate, are another story. Zircon crystals are extremely durable, resistant to melting, cracking, dissolving, or crushing, and able to withstand repeated cycles of metamorphism and erosion. This makes them the longest lasting—and oldest—minerals on Earth. If that’s not impressive enough, they also have a natural cloc...

Yellowstone was the first national park in the world, designated by the U.S. government in 1872. Before then, it was travelled by explorers and fur trappers. And for 11,000 years before that was a hunting and camping ground for indigenous tribes. But perhaps the most fascinating part of its history occurred when it was formed. When you visit Yellowstone, you’re standing above a geologic hot spot in the Earth’s mantle. Two million years ago, this hot spot created supercharged lava, in magma c...

In the remote desert town of Coober Pedy, in South Australia, summer temperatures can reach 127 degrees—so hot that many residents live below ground, where the temperature is a constant 75 degrees. This tradition began 100 years ago when the first opals were discovered, and so was born an underground cottage mining industry that endures today. Only 5 percent of opals found worldwide are designated as precious, with a fiery play of color within them, and 95 percent of those come from Australia....

Fjords are deep valleys with steep sides, formed by glaciers. They’re usually on the coasts of continents and filled with water. Over the past five million years, glaciers have migrated over continents then melted back, nearly 50 times. Modern fjords formed during the last glacial advance, from around 100,000 to 20,000 years ago, when glaciers covered a quarter of all land on Earth. Since so much water was locked up in glaciers, sea level was 400 feet lower than today. In the high latitudes,...

In January 2022, the largest volcanic eruption since Mount Pinatubo happened. And few people noticed. That’s because it occurred in the remote kingdom of Tonga, made up of tiny, sparsely inhabited islands in the South Pacific. But that doesn’t mean it wasn’t important. It produced the highest eruption cloud in modern times, and changed the way scientists view the interaction between volcanoes and the atmosphere. Here’s what happened: the volcano’s vent was 500 feet below sea level. As it erup...

Octopuses are incredible, almost otherworldly creatures. They can change their color, shape and texture in less than a tenth of a second—making them masters of camouflage. With no bones, they can squeeze their entire bodies through tiny openings—making them great escape artists. They’re highly intelligent and demonstrate short- and long-term memory. They learn to recognize people and have even been trained to operate a camera to take their picture. They play, use tools and solve problems. Th...

The oldest individual trees are conifers—but they’re not the famous sequoias. Some of those exceed 3,000 years. But bristlecone pines are centuries, even millennia, older. They’ve adapted to small, high and dry ranges in eastern California, Nevada and Utah, just below the tree line. The oldest trees live in the harshest conditions, where few other plants can grow, so they’re less likely to be exposed to fire, insects or disease. And the oldest of them all was a tree named Methuselah. Bristlec...

A thousand years before the Inca, in the deserts of Peru where rainfall is almost nonexistent, lived a civilization so advanced they’d figured out how to use wind to pump water. The Nazca people were fantastic artists, famous among anthropologists and ancient art collectors for their textiles and ceramics. But they were also brilliant engineers. Over generations, they constructed a sophisticated water system. They trenched and tunneled into the gravelly water table of the Andean foothills, th...

Besides a few very committed scientists, there’s only one organism that can live on the continent of Antarctica year-round. It’s not a penguin or a seal; they live mostly at sea. No, it’s the tiny Antarctic midge, just a quarter inch long and extremely adapted to the extreme environment. Midges are small insects that usually fly and bite hosts to feed on blood. The Antarctic midge does neither. Like many insects in very windy places, it has lost its wings to keep from being blown away—and her...

On November 1, across Latin America but especially in Mexico, the cemeteries come alive—with a celebration. It’s Dia de los Muertos, the Day of the Dead. Legend has it the gates of heaven open for a day to allow the souls of the dead to reunite with loved ones. It’s considered disrespectful to mourn the dead, so families bring food and drink, clean and decorate gravestones, sing, and dance, fly brightly colored kites, and tell stories about and for the deceased. Dia de los Muertos is a meldin...

Here are two trivia questions for you: What’s the strongest metal on Earth? And why is it called “wolf cream”? It was discovered in the 1400’s when miners found a hairy black mineral with tin ore. When they smelted the two together, the surface of the melted ore foamed and a heavy slag consumed much of the tin. They named the mineral “wolf” for its furry appearance and appetite for tin and “rahm” or cream for the foam. Wolfram. In Europe, it’s still called that. But elsewhere, it has a name g...

Mesopotamia, in the Middle East, is known as the birthplace of civilization. Two of its early civilizations mysteriously collapsed, which baffled researchers until they found the reason—in stalagmites. Around 10,000 years ago, hunter-gatherers there developed agriculture and domesticated animals. Abundant food and animal labor allowed them time to invent: the wheel, glassmaking, and eventually writing. This set the stage for the world’s first empires: the Akkadians then the Neo-Assyrians contr...

As we know, birds descended from dinosaurs. And with 18,000 species of bird now living, there may be more “dinosaur” species today than ever before. The birds that share the most DNA with their dinosaur ancestors are, surprisingly, the chicken and the turkey. The turkey, like the tyrannosaur, has a wishbone and a similar hip structure. And it has meaty drumsticks and thighs like a Velociraptor. Yum! The turkey probably evolved from prehistoric birds in South America and migrated northward. Du...

We’ve talked before about how lightning breaks nitrogen molecules into nitric oxide—which falls to Earth in rainwater and nourishes plants. But we now know that lightning storms have another essential function. After forming nitric oxide, a secondary reaction makes oxidants, which clean the atmosphere. Oxidants are essentially water molecules that lost a hydrogen atom. To replace it, they react with other compounds, including methane and CO2. They oxidize these into other forms that also fal...

Whakaari/White Island is New Zealand’s largest active volcano. Its crater forms a huge natural amphitheater that opens to a bay. In December 2019, a large group of tourists arrived for a day trip. They donned gas masks to watch fumaroles spew clouds of yellow steam. Then, disaster struck. The volcano erupted suddenly, belching vapor and ash two miles into the sky. The cloud collapsed into the amphitheater, which funneled it directly at the tourists. Half were killed and the other half suffere...

We’ve talked a lot about fossils on EarthDate, but we’ve never talked about how they form. Normally, when a plant or animal dies, it decays or is consumed. But occasionally its remains are preserved as a fossil. This usually happens when the organism is buried quickly in sediment. The sediment layer protects it from the elements, scavengers, even oxygen. Often soft parts decompose, leaving bones, teeth, shells, or exoskeletons. As the sediment gradually hardens into rock, mineralized water is...

Until Marie Tharp came along, no one knew what the seafloor really looked like. It was long thought to be a featureless plain of mud. Then sonar, invented in World War II, began to give us a glimpse. But it could only “read” the bottom of the ocean right below the ship’s path. Marie Tharp earned master’s degrees in geology and mathematics in the 1940’s and joined the navy to study the seafloor—but women were not allowed on research ships. Instead, she was assigned to process and analyze new ...

Bloodletting with leeches seems a very primitive practice. So, it may surprise you to know it’s still very much in use today. There are 700 species of leech. Most dwell in water and drink blood from fish, turtles, ducks, frogs and other creatures. Scientists can even track which animals are living in swamps and rainforests by capturing leeches and DNA testing the blood in their stomachs. Leeches were first used in medicine at least 2,500 years ago. They became so popular in nineteenth-century ...

DNA is like a fingerprint. Each species’ DNA signature is distinctive. And it can be found on the scene long after the individual has gone. For some time, scientists have gathered the DNA that organisms leave behind—in saliva, urine, feces, fur, and flakes of dry skin—to detect their presence and study them. They’ve found this so-called environmental DNA, or eDNA, in water, soil, even snow. But scientists wondered if they could gather it more easily and broadly by capturing it out of thin air...

When the explorer Ferdinand Magellan finally made it ‘round the treacherous horn of South America in 1521, the ocean beyond seemed especially calm—so he named it the peaceful sea: Mare pacificum, the Pacific Ocean. Little did he know the Pacific is anything but. It’s surrounded by more than 1,000 volcanoes that make up what’s now called the Pacific Ring of Fire—a geologically active strip 25,000 miles long, in places 300 miles wide, that borders the Pacific on three sides. It would be more tha...

Think about this: a tree could be 100, 200, more than 300 feet tall, yet can lift water from deep underground all the way to the leaves of its highest branches. Each day it could move hundreds of gallons, several tons of water this way. This gravity-defying feat is made possible not so much by the tree but by the properties of water itself. Trees perform photosynthesis in their leaves, which requires water. The hydrogen in water goes to form carbohydrates—sugar, the food for the tree. The oxyg...

There’s a common houseplant that in the wild can do what no other plant can. It’s the staghorn fern. It’s an epiphyte, meaning it doesn’t need soil but instead grows on a larger host plant and draws its nutrients from water and air. But that’s not what makes it unique. Normally a staghorn has two types of fronds. One is green, antler shaped and produces spores. The other is brown, strap-like and sterile, and attaches the fern to the host. But a scientist noticed that wild staghorns in Austr...

You’ve probably heard that black cars get hotter than white cars. Scientists set out to measure the difference. They parked two otherwise identical cars in a sunny parking lot, and, sure enough, the white car’s interior stayed 17 degrees Fahrenheit cooler. Urban planners hope to use the same principle to cool cites, where miles of black asphalt and dark colored roofs absorb the sun’s heat, amplifying daytime temperatures, then radiate the heat through the night. The famous white villages of S...

There’s a special place in South Africa called Border Cave where our ancestors already in modern human form lived continuously for nearly a quarter million years. Excavating in the cave is like reading backward in a history book, finding evidence of each earlier generation in each deeper layer. The cave has yielded 69,000 artifacts, a treasure trove of clues to human prehistory, and digs continue to this day, with surprising new findings. For instance, scientists recently discovered the remai...