Episodes

We often think that Thomas Edison invented the light bulb. While he certainly was the first to make it a commercial success, the invention took almost a century to “come to light.” The story begins long before household electricity. In 1800, an Italian scientist named Volta created the first primitive battery. And one of the first things he did was connect copper wire to it, which glowed faintly. Two years later, a different inventor ran current from a battery through carbon rods to create the f...

Plains Indians depended on buffalo for everything: meat for food, hide for clothing, horns and bones for weapons and tools. One of the ways they hunted them was by stampeding them over cliffs. Scientists thought that humans practiced communal hunting drives like this as far back as 5,000 years ago. But a recent discovery has changed that. When constructing a new airport north of Mexico City, workers unearthed enormous bones and called in scientists, who discovered two massive pits 80 feet in dia...

The greatest environmental disaster in American history lasted for eight years and displaced more than 3 million people. What was it? The Dust Bowl—which refers both to this event and the place where it happened: some 100 million acres in Kansas, Colorado, Oklahoma, New Mexico, and Texas. This area normally sees just 20 inches of rain a year. High winds from the Rocky Mountains roll across it. Summers bring scorching heat; winters bring Arctic blasts from Canada. Explorers called it the Great Am...

Earlier, we talked about the run-up to the greatest natural disaster in American history, the Dust Bowl. Between 1870 and 1920, settlers poured into the Great Plains, plowed under native grasses, and planted grain. Then in 1929, the Great Depression struck, and grain prices collapsed. In 1931, a long drought set in. Farms failed across the region. Millions of acres, stripped of grass and barren of crops, lay untended. The fierce prairie winds carried the dry topsoil high into the sky in roiling ...

Deep within our planet, intense heat left over from Earth’s formation is stoked by the continued decay of radioactive isotopes. In a few places, like Iceland, geologic features allow this heat to come close to the surface. Here, it often turns groundwater to steam. For a century, Iceland has been tapping into this naturally occurring steam and using it to heat the homes, streets and sidewalks of Reykjavik. Or to run power plants to make electricity. Now, Iceland is trying to take it a step furth...

You may have heard that monarch butterflies migrate from Mexico to Canada and back. But you may be more amazed to know that the returning butterflies are the great-great-grandchildren of the butterflies that left. Here’s how that works: The first generation of monarchs leaves Mexico in the spring, pausing to breed and lay eggs as they fly northward. Their eggs hatch into caterpillars, which eat for two weeks, then metamorphose into butterflies. In four weeks, they too are flying northward. As th...

We call Earth the Blue Planet because it’s covered in water—but what makes water blue? And why is it not blue in your glass or your ice cubes? Water has many rare properties, some of which we’ve covered on previous episodes. But this property, its blueness, is unique to water and goes right to its core. It’s the only molecule in the universe that vibrates a color. How is that? The water molecule is made up of two atoms of hydrogen and one of oxygen. The hydrogen atoms are very lightweight, but t...

California is well known for droughts. But it also had one of the greatest floods in U.S. history. In 1861, California had been in drought for 20 years. Most of the state’s residents lived around San Francisco and in the Central Valley. Ranchers there had been praying for rain for two decades. In November, they finally got it. First, winter came early, bringing heavy snow to the mountain range that bounds the valley. In December, temperatures rose, the snow melted and drained into the valley, sa...

Previously, we talked about California’s 1861 super flood that turned its Central Valley into an inland sea. That flood was caused by an ARkStorm. The A R in Ark stands for Atmospheric River. Atmospheric rivers are layers of water vapor that form in the tropics and circle the globe. They’re very large—up to 2 miles high, 500 miles wide and 5,000 miles long. Each can carry 15 times the flow of the Mississippi River. Atmospheric rivers are always forming, and always flowing—until they hit somethin...

The pangolin is one of the world’s most unusual animals—and one of the most heavily poached. An adult pangolin is 3 to 5 feet long and eats some 70 million ants and termites a year, using a tongue that’s longer than its body, covered in sticky saliva. It burrows into termite mounds and anthills and can close its ears and nostrils to keep angry ants at bay. That may sound like an anteater or an aardvark. Except, the pangolin is completely covered in scales. It’s the only mammal that has them. The...

Recently, a group of sailors in the South Pacific encountered something extraordinary. One minute they were sailing in water. The next, in a sea of rocks. Floating rocks, some the size of basketballs, as far as the eye could see. Imagine their amazement! Turns out the rocks were pumice, which was extruded by an undersea volcano near the island of Tonga. Pumice is molten rock filled with gas bubbles, ejected at high pressure like whipped cream from a can. When it hits the seawater, it hardens ins...

Human life has always depended on salt. Chemically, and culturally. All animals need it for the function of blood, organs, muscles and nerves. Carnivores get it from eating other animals. Herbivores get it from salt licks and minerals in groundwater. For millennia, humans have used salt to preserve meat—and still do today. This works because salt, in abundance, kills bacteria. When we pack meat in salt, it draws water from the cells. Water naturally moves across cell membranes to try to reach an...

Mass extinctions have happened throughout Earth’s history, sometimes wiping out the large majority of all life on Earth. Each spelled the end for millions of species—and the beginning for millions more that evolved to take their places. On earlier EarthDates, we talked about the asteroid that smashed into Earth, ending the reign of the dinosaurs while opening the door for mammals. But there was an earlier event that appears to have created the same opening for dinosaurs themselves. Around 250 mi...

Opinions are divided on eucalyptus trees. In some places, they’re a fast-growing cash crop. In others, they’re an invasive species. In Australia, where the trees originate, they’re about to become more popular because they may lead miners to gold. In Australia’s dry climate, eucalypts send roots down hundreds of feet looking for water. In gold mining areas, scientists have found microscopic gold flakes, thinner than a human hair, in the tissues of their leaves and on the waxy residue that coats ...

Getting caught in quicksand can be fatal, with victims dying mostly from dehydration, hypothermia or heat exhaustion. What can you do to avoid getting trapped—and to escape if you do? It starts by knowing where quicksand forms and what it looks like. Quicksand is just super-saturated sand. Normal wet sand is about 25 percent water; quicksand is more than 70 percent. Quicksand can form on beaches, tidal flats, riverbanks or near springs—anywhere the ground is saturated with water. In those places...

Each year, millions of pebble-sized meteors strike Earth’s atmosphere and burn up harmlessly. But once a century, a house-sized meteor makes contact—and explodes in the air with devastating results. In 2013, one such airburst occurred in Russia. The Chelyabinsk meteor broke apart miles above the surface, with 30 times the force of the Hiroshima atomic bomb. It blew out a million windows over 200 square miles and injured 1,600 people. In 1908, near the remote Russia-Mongolia border, a larger airb...

At midnight, at the end of the year, Earth celebrates the completion of two cycles. The first, of course, is Earth’s rotation, turning day to night and back again. To complete this cycle, Earth rotates at 1,000 miles an hour, counterclockwise. Not all planets spin this way. Venus rotates the opposite direction, and Uranus spins at 90 degrees to its orbit. But pretty much everything in the universe spins. The second cycle of course, is Earth orbiting the sun. The Solar System began as a cloud of ...

Once an ice skater gets going, friction between her skate and the ice creates a microscopic layer of water that allows the skate to hydroplane. But before she can get up to speed, and friction can melt the ice, it’s still slippery enough for her to start her glide. Why is ice so slippery? In the 1800s, scientist Michael Faraday conducted experiments to show that ice, even well below freezing, has a very thin layer of water on its surface. But the technology to see this layer did not exist. Nor d...

In 1911, Robert Scott and Roald Amundsen led expeditions to Antarctica, both hoping to be first to the South Pole. Amundsen’s crew left 20 days before Scott, using sled dogs. Scott’s team took a different route, using motorized snow tractors, hoping to speed their passage. After 77 days, Scott and his men finally reached the pole—only to find that Amundsen had beat them to it. With great disappointment, they turned back to their ship … when disaster struck. The temperature plummeted as the Antar...

There are over 1 million avalanches every year, but they kill only 150 people. So, while it’s very unlikely you’ll get caught in one, here are a few safety tips, just in case. Avalanches happen when a slab of unstable snow breaks off from the layers beneath it. If you’re on top of that slab when it happens, ski or run for the sides. Same thing if you’re in its path. Avalanches can reach 80 miles an hour in 5 seconds, and top 120 miles an hour. You won’t be able to outrun it, so head for the side...

Maybe only Santa’s reindeer can fly—but regular reindeer come pretty close. They can fly over the tundra at 50 miles an hour, covering more than 20 miles a day. Their annual migrations span 3,000 miles, the longest of any land animal. And they’re spectacularly adapted for that life: Their eyes change color depending on the season. In their summer above the Arctic Circle, with nearly 24 hours of sun, their eyes turn gold, to reflect the harsh light. In the dark months of winter, their eyes turn b...

There are hundreds of thousands of species of beetle, but only one species of human, and koala, and aardvark. Homo sapiens evolved around 300,000 years ago, when there were at least three other species of the genus Homo on Earth. By 40,000 years ago, we were the only one left. But at least we have great ape cousins in the hominid family. There are other species on Earth that are even lonelier, the last branches of their family trees. Koalas live only in Eastern Australia—the only species and the...

On another episode, we talked about species that are the last of their family tree. Well, here’s one that’s the last in its genus, in its family, even in its order. The tuatara is a 2-ft-long resident of New Zealand. It may look like a lizard, but it diverged from modern lizards and snakes 250 million years ago, and it’s quite a different animal. To start, it’s adapted to cold weather. The tuatara can thrive when its body temperature is just 40 degrees Fahrenheit. It hibernates through winter, b...

Geothermal energy comes in three varieties. The first and most widespread is low-temperature heat—found everywhere, just below the surface—which can be used to maintain a constant temperature in buildings. The second is much rarer: extreme heat found near volcanoes and fault zones, where high temperatures from deeper within Earth come close to the surface. These can produce steam to run electric power plants. We’ll talk about both these types on future EarthDates. The most commonly used geotherm...