Episodes

Recently, scientists discovered the fossil of a hadrosaur, a duckbilled dinosaur, which was bitten by a Tyrannosaurus. A bite on a fossil is not that unusual, but this one helped settle an argument. Over the past few decades, some paleontologists maintained that T. rex was a ferocious hunter. Newer theories pointed to his useless forelimbs, small eyes, and huge olfactory chambers. He wouldn’t have been able to grasp prey and may have had poor vision—but he would have been able to smell a rotting...

In the 1970’s, the Viking rover landed on Mars and detected no life. In 2003, NASA took the same technology to the Atacama Desert in Chile and got the same reading. Was there really no life there? And by extension, no life on Mars? You might think that the driest place on Earth is the Sahara. But they’re actually polar deserts, like the McMurdo Dry Valleys of Antarctica, and high deserts, like the Atacama. There are places there where it hasn’t rained in 500 years—if ever. Surprisingly, the drie...

Imagine you’re in Chile’s Atacama Desert, the driest nonpolar desert in the world. Understandably, you’re parched. So you head to the local watering hole…where you’re surprised to find a craft beer—made from fog. What? Deserts have little rain, but if they’re near the coast, they can have fog—which you may remember is just a cloud on the ground, water vapor condensing around particles in the air. In the Atacama, fogs often roll in from the Pacific, but the water droplets are too small to produce...

In school, we learned the continents: the Americas, Eurasia, Africa, Australia, and Antarctica—with island nations like New Zealand floating off by themselves. So you may be surprised to hear that scientists have discovered a new continent—and New Zealand is part of it, after all. In fact, it’s one of the only parts of what’s now called Zealandia that’s above sea level. Most of Zealandia, which is almost two-thirds as big as the continental United States, is more than a kilometer underwater. Tha...

Many ancient cultures have stories of fantastic creatures. Did all these people simply imagine dragons, gryphons, or giants? Today, scientists believe they found fossils and, unable to explain them, gave them exaggerated features of the animals they knew and found places for them in folklore. For instance, we know Greeks and Romans collected fossil bones. They believed these once belonged to their gods and warrior heroes, who were hailed as giants when the huge bones were found. These fossils, n...

From a previous EarthDate, you may remember that some mythological creatures were born when ancient cultures discovered fossils and created stories to explain them. Well, here’s a famous beast that started as a tiny elephant. During the Pleistocene ice ages, polar ice and continental glaciers held more of Earth’s water, causing sea level to fall. During low sea-level periods, elephants from Africa walked and swam across a nearly dry Mediterranean to Europe. Once seas rose again, some were trappe...

The water cycle makes life on Earth possible. And what makes it possible are the incredible properties of water itself. Earth is the only planet we know of where the three phases of water—solid, liquid, and gas—are present on its surface. That’s partly because those three phases exist in a narrow temperature window. And the middle phase—liquid water—corresponds to much of Earth’s surface temperature. This allows our oceans to exist, which are the key reservoirs of the hydrological system. Winds ...

Just how likely are you to be struck by lightning? And what can you do about it? In another EarthDate, you heard how lightning is essential to life on Earth. It frees up nitrogen in the atmosphere to make it available to plants, which form the base of our food web. For that to happen, you’d think there must be a lot of lightning. And you’d be right. Storms around the world produce about a billion and a half lightning strikes each year—which hit about 20,000 people. Of them, only 10 percent, or 2...

Next time you hear a bird singing, stop for a second to listen. Even the most common birds can do amazing things. The cardinal, for instance, has the range of a piano, though higher on both ends. And he can span it in a tenth of a second. No human can come close. The wood thrush can sing one note, a different note on top of that, and trill them both independently. It’s like a soprano duet in one 2-oz animal! How can they do these incredible things? The secret is their voice box. Our larynx has o...

You’ve probably heard of adventurers skiing down the highest mountain in the world. But did you know that elite cyclists can actually ride up it in a day’s time? Then race down at 80 miles per hour? You probably guessed that I’m not talking about Everest. It’s still the tallest when measuring purely by height above sea level, or altitude, at just over 29,000 ft. But by other metrics, there are other contenders. If you measure from the center of the Earth, the highest mountain is near the equator...

Just how rare are rare earth elements? It depends on their price. There are 17 REEs, with funny names like gadolinium and dysprosium—and all of them are metals. Their special magnetic, thermal, and corrosion-resistant properties have led engineers to use them in our most familiar electronics. The rarest ones are still 200 times more plentiful than gold. And the most common are as abundant in the Earth’s crust as nickel, zinc, or lead. The challenge is that they’re rarely concentrated enough to m...

The Earth has 3 million earthquakes a year, 8,000 every day. And some are caused by humans. The crust of the Earth is composed of many tectonic plates, which are always moving. As the plate boundaries collide, grind against, or pull apart from each other, the crust cracks, creating fault zones. As stress builds up, the plate boundary faults can open or slide, causing natural earthquakes. The vast majority are too small to feel, but some can be major. Sometimes human activities can trigger an ear...

When you look at a cloud, you’re actually looking at billions of microorganisms. Ever since Darwin found microbes in dust over the Atlantic, they’ve turned up in ever-stranger places: In dust plumes over mountains. In high-altitude snowfields. And in the tops of clouds. This means, of course, they’re also in rain. Scientists have identified thousands of species of microbes and fungi living in rain and clouds—able to withstand the harsh temperatures, low oxygen and punishing radiation of the atmo...

The Mediterranean Sea: birthplace of European civilization, and still its favorite vacation spot. You’d never know that, not too long ago, it was a desert filled with salt, with temperatures over 150 degrees. About 6 million years ago, growing ice sheets in Antarctica began to trap Earth’s water and lower sea levels. Waters in the Strait of Gibraltar, that narrow channel between Spain and Morocco, began to recede. Freed from the weight of the water, the land began to rise. Which caused a feedbac...

In one of the world’s deepest mines, scientists have discovered some of the world’s oldest water. In northern Canada, the Kidd Creek Mine is almost 10,000 ft deep. Here, miners search for copper, zinc, and silver ore in volcanic material that was once the floor of an ancient sea. At the very bottom of the mine, they drilled an exploratory borehole even farther down to look for more metal ore. What they found was possibly the oldest water in the world, trapped in the rocks for more than 2 billion...

Strange weather around the world is often blamed on El Niño. Who is this “boy,” and how does he cause so much trouble? El Niño is simply warmer-than-normal water in the Pacific, off South America. It was first noticed by sailors in the 1600s, who named it after the Christ Child since it came in December. We now know that El Niño lasts several months to several years, returns every 2 to 7 years, and is caused by atmospheric pressure. In a normal year, high pressure over the Pacific and low pre...

You probably learned in school that the first Americans came from Siberia, crossing the Bering Strait into Alaska. That ancient history is still widely accepted—but it has a few new wrinkles. Archaeological records now show that humans left Siberia 25,000 years ago but didn’t arrive in North America till 15,000 years ago. Where were they for 10,000 years in between? New research suggests they were living in the Bering Strait, in a now-submerged land called Beringia. During the peak of the last I...

Humans have wondered about the age of Earth for centuries. In the 1600s, a bishop worked backwards through generations of “begats” in the Bible to come to a very specific date for Creation: October 26, 4004 BC. At 6 PM. In the 1700s, scientists developed their own theories. Recognizing that different layers of rock represent different periods in Earth history, they calculated a much looser estimate: 1 million to 1.6 billion years old. By the early 1900s, scientists began to understand radioactiv...

Humans have been painting to memorialize their lives since the Stone Age, using techniques that endure to this day. The earliest art supplies we’ve found—abalone shells full of ground ochre and charcoal—were in the Blombos Cave in South Africa, and are up to 100,000 years old. But we haven’t yet found paintings to go with them. By 40,000 years ago, tribes in Europe, Australia, and Indonesia painted images of hunters and herders on cave walls, and had expanded their palette to include many colors...

Since 2000, the Arctic has warmed more than other areas, up to 5°F. And that’s beginning to melt the permafrost. In the Arctic winter, the earth is frozen, from tens to thousands of feet down. In summer, the top several feet melt, creating a so-called active layer where plants can take root. Below that is permafrost: frozen soil that contains a great deal of ice. For these regions, it’s like bedrock—stabilizing the active layer and providing a solid footing for buildings. But as the melting reac...

Grains of pollen are like Mother Nature’s fingerprints, allowing scientists to track the migratory paths of dinosaurs and solve long-cold murder cases. Flowering plants evolved 100 million years ago, and within 30 million years dominated the planet. Today, there are almost 400,000 species. One reason for their global success is their remarkable fertilization system. A single flower can produce hundreds of thousands of pollen grains, which can be distributed by the wind, insects, or animals, fert...

California’s Central Valley is an agricultural bonanza, producing a third of America’s food crops. But it’s facing serious water challenges. The valley floor is 20,000 sq miles of some of the most fertile soil on Earth. Here, the sun shines 300 days a year. More than 250 different crops grow, worth $17 billion per year. The valley was developed into farmland around the turn of the twentieth century. When farmers arrived, they began to drill wells into the fresh-water aquifers below. By the 1930s...