Episodes

Amazingly, the structure of most living things, and many other things as well, conforms to one sequence of numbers. It was described in the 1200s by Italian mathematician Leonardo Pisano, also called Fibonacci, working from earlier Indian ideas. The Fibonacci Sequence is 1, 1, 2, 3, 5, 8, 13 and onward – where the first two numbers, one and one, add up the next number, two. The next two numbers, one and two, add up to the next number, three. And so on. Most flowers have three, five, eight or ...

What’s the world’s most dangerous animal? Sharks? Nope, they bite only 70 people a year, with just six fatalities. Poisonous snakes? They kill about 50,000. But far and away the most dangerous is the mosquito. It kills a million people a year, and sickens 250 million more! But we may be able to stop it, with an even tinier creature. There are 3,000 species of mosquito. Different ones can carry malaria, West Nile virus, Zika, yellow fever, dengue, Japanese encephalitis, and more. They don’t c...

Thought to have been extinct for over 2 million years, a cluster of Wollemi pine was discovered by hikers in a secluded canyon outside of Sydney, Australia in 1994. Guarding this area from humans and fire along with cultivation and conservation efforts by botanical gardens have safeguarded this unique species. Now, advances in decoding the Wollemi pine genome may provide the secret to successfully preserve this critically endangered species.

Grand Teton National Park contains North America’s youngest mountain range: the towering “Tetons.” While the range formed by extension along a tectonically simple “normal” fault, the Teton Fault is unique because it has moved nearly 33,000 ft (10 km) in just ten million years. Preserving astounding natural beauty and a human history stretching back at least 11,000 years, the national park was first established in 1929.

Sometime long ago, a small meteorite crashed into the sands of the Sahara. In 2011, scientists discovered it and dubbed it NWA 7034 – nickname: Black Beauty. It was soon recognized as the rarest meteorite on Earth. Black Beauty came from Mars. Scientists know that because oxygen isotopes trapped within it match those in the Martian atmosphere. Because that atmosphere is so thin, Mars is not well protected from asteroids. When they impact the surface, they explode off chunks of rock. Some of th...

The blast was over a thousand times stronger than Hiroshima, heard 700 miles away. It killed 57 people and countless animals. This was the eruption of Mount St. Helens 45 years ago in Washington, the deadliest, most damaging volcanic event in modern US history. Surprisingly, in America today there are 169 active volcanoes. Most are in Alaska. A few in Hawaii have small eruptions regularly. There are 20 volcanoes in Washington and Oregon, where the Juan de Fuca tectonic plate subducts under No...

Snowpack provides our water, especially in the American West. And new research shows wildfires may be affecting it. Snow accumulates in the mountains in winter, then melts in spring to fill rivers. As we’ve discussed in prior EarthDates, that runoff is critical to water supplies, for irrigation, fisheries and cities. Earlier melting, due to more winter rain, has brought spring floods. This can mean lower water supplies in summer and fall. Now wildfires have been shown to also promote earlier m...

We’ve all seen geodes, and marveled at their beautiful crystal interiors, but do you know how they form? Geodes occur mostly in lava and sedimentary rocks. In molten lava, gas bubbles and lava tubes form, some quite large. They become voids as the rock hardens, and can fill with mineral-rich fluids. Over many years, minerals precipitate out, and crystals line the void. As more fluids seep in, more crystals grow. Geodes that form in lava often contain quartz crystals, especially amethyst, whic...

The Wallace Line, a boundary separating the unique species of Australia from those of Southeast Asia, has long fascinated scientists. Exploring the influence of plate tectonics, glacial periods, and geographic isolation may hold the answer to this mystery.

Ancient heating and cooling systems operated without electricity, which could today provide solutions for climate control in places without electricity or where outages have become more common. Wind towers that capture wind or thick walls can work to passively cool or insulate buildings. Southern facing windows with shading devices, and adobe construction, can keep homes warm or cool depending on the season. Rainwater collection systems can store water through dry periods.

Oxygen. Without it, life on Earth would look very different. Because only plants and a few types of microorganisms can live without it. Fortunately, plants originated 3.5 billion years ago. They inhaled so much carbon dioxide and exhaled so much oxygen that they changed Earth’s atmosphere. With more oxygen in the air, Earth could sustain animal life -- which would eventually become us. Those first plants looked a lot different than you might imagine. They were phytoplankton, single-cell algae ...

Two of the most important geologic features of our planet, that shape our oceans and continents, are Earth’s two types of crusts – oceanic and continental. Both types float on Earth’s asthenosphere – its semi-molten mantle. Oceanic crust is thin, averaging just 5 miles thick. It rises out of the mantle at mid-oceanic ridges and sinks below continents at subduction zones. It’s constantly being recycled like this, and is therefore relatively young. Our most ancient oceanic crust is just 180 mil...

For 99% of hominin history, we were living in the Stone Age. It began some 3 million years ago, followed much later by the Bronze and Iron Ages, at just 10,000 and 5,000 years ago. Hominins have used wood throughout those ages. For all that time, you could say we’ve been in a Wood Age -- though scientists never officially named one. Wooden artifacts don’t often turn up in the archaeological record, because they decompose. Nonetheless, traces have been found. Some stone tools in East Africa, d...

Antarctica is a continent of extremes and superlatives. It’s the coldest continent, with Earth’s lowest recorded temperature of 130 below zero Fahrenheit. It’s the driest continent, with just 6 inches of precipitation a year. It’s the windiest continent, with gusts up to 200 miles an hour. Surprisingly, it’s the highest continent, with an average altitude of 8,200 feet, largely due to ice sheets up to 15,000 feet thick. It also has an extreme range of geologic age, with rocks nearly 4 billi...

Like the legendary unicorn it resembles, the narwhal is an enigma. It lives only in Arctic waters, in a frozen seascape far from civilization, making it hard to study and therefore not well known to science. For instance, we don’t know what it does with its most distinctive feature. We do know that its 6- to 10-foot tusk is actually a single tooth, which grows through its lip and continues growing throughout the narwhal’s life. And that narwhals living farther north have thicker tusks than t...

Anyone who’s been in an airplane has heard that constant roar of flight. That’s partly the engines—but the noise comes more from air rushing over the wings. Anyone who’s seen an owl fly… hasn’t heard anything. Because unlike an airplane, owls fly almost silently. How do they do this? Aeronautical engineers have examined owl wings and found several features working together: The leading edge of the wing, called the comb, is finely serrated, to break up the air flowing over it. The middle of t...

Water is heavy. When we move enough of it, it can change the tilt of Earth’s axis. It’s that axial tilt that creates our seasons. And the tilt is always changing, due to changes in Earth’s gravity. Natural phenomena like earthquakes and volcanoes can redistribute the weight of continents, affecting Earth’s gravity. But so can the movement of water. Researchers recognized that water melting out of glaciers and ice sheets into the ocean had redistributed the weight of that water from the colder...

Many animals hibernate, but only the wood frog can freeze solid in winter—its heart and brain stopping completely—then thaw and come back to life in the spring. Its process to do this is fascinating … and could one day save human lives. The danger with freezing is ice. If water freezes within a cell, sharp ice crystals will puncture or rupture cell walls and kill the cell, which normally kills the animal. So, as temperatures drop, the wood frog’s liver converts glycogen to glucose, a sugar sy...

One of the great mysteries of the pyramids may have been solved—by state-of-the-art radar systems that can penetrate the desert sand. The Egyptian pharaohs built 90 pyramids, with the most famous, at Giza, constructed almost 5,000 years ago. At nearly 500 feet, the Great Pyramid of Khufu was the world’s tallest manmade structure for almost 4,000 years! To build it, 20,000 workers assembled 2.3 million stone blocks, each weighing tons. Scientists have long wondered how ancient people, without ...

After the dinosaurs, giant mammals ruled Earth for millions of years—then suddenly, most of them disappeared. What happened? When the Chicxulub asteroid struck, and plunged Earth into darkness and cold, large dinosaurs became extinct. Early mammals—small, warm-blooded and covered in fur—were able to survive. And, over a few million years, they grew in size to occupy the environmental niches the dinosaurs had vacated. There were bears the size of rhinos, and rhinos the size of elephants. There...

For many thousands of years, humans have used medicinal plants to help heal wounds. It turns out, some of our primate relatives may have, too. In Indonesia, scientists observed a large male orangutan with an open wound on his face. To their surprise, he sought out a special plant called akar kuning that orangutans usually do not eat. He consumed a large quantity of leaves, then chewed more into a paste, applied it to the wound and left it there. Within five days, the wound had closed. Within ...

Turns out it was much easier to go to outer space than to inner Earth. In the 1950s, the U.S. and Russia began competitive spaceflight programs. Twenty-five years later, the U.S. Voyager spacecraft had gone 10 billion miles into space. Around the same time, both countries also began drilling programs trying to pierce through Earth’s crust to reach the mantle below. The U.S. project began drilling off the coast of Mexico, because scientists had recognized that oceanic crust is thin, averaging ...

In the deepest, darkest ocean, caustic, superhot water teems with life. In the rest of the ocean, the food web is built on photosynthesis. Phytoplankton takes in sunlight and carbon dioxide to give food and oxygen to everything else. But with no sunlight, these deep ocean communities thrive by chemosynthesis—they consume chemical compounds. In the 1970s, scientists were amazed to discover previously unknown species of shrimp, clams and tube worms living on so-called black smokers. These are ...

The Moon has inspired humans for countless generations. Among moons, ours is large, about a quarter the size of Earth. But we have only one. Other planets have many. And some have none. Where do they come from, and how do planets acquire them? Our moon is unique in the solar system. It came from an impact, when an asteroid the size of Mars slammed into Earth 4 billion years ago and smashed off a body that would become the Moon. Other moons are ancient astral bodies that were created along wit...