Episodes

In another episode, we talked about the horseshoe crab, which has existed on Earth nearly unchanged for more than 400 million years. In the last 40 years, it’s become a vital player in our medical industry. Why? It’s in their blood. Horseshoe crab blood is copper based, not iron based like ours, which makes it blue. It coagulates so rapidly and completely around invading pathogens, that medical researchers realized it could be used to detect pathogens for us too. So they isolated the coagulating...

You might have heard of your microbiome, but did you know you also have a virome? That’s right, there are more than a trillion active viruses within you right now. Viruses exist in every organism, in every environment. There are at least ten times more viruses on Earth than all other biological entities combined. A virus is a tiny packet of RNA or DNA, about 1500 times smaller than a grain of salt. They lack the ability to reproduce or the ribosomes to make energy. Many scientists don’t even con...

To Egyptians and ancient Greeks, amethysts were as precious as diamonds, rubies, and sapphires. The stone was thought to cool tempers and prevent drunkenness, so it was cut into jewelry for wise kings and crafted into wine goblets for those who hoped to stay sober. In the Middle Ages, it adorned the rings of religious leaders and the scepters of royalty. Since then, huge finds in many places, especially Brazil and Uruguay, have made amethyst plentiful and affordable. And that’s good, because thi...

Dr. Gene Shoemaker mapped the moon, trained astronauts and discovered more than 800 asteroids. He was also the first person to go to the moon… and stay there. Shoemaker started his career with a bang, proving with his Princeton dissertation that the mile-wide Barringer Crater in Arizona, previously attributed to volcanic activity, was in fact the result of a meteorite impact. Soon after, he founded the astrogeology program of the U.S. Geological Survey, in part to better understand the potential...

When scientists mapped the human genome, they found that just 2% of it controlled our own functioning. Fully 8% was the DNA of fossil viruses. Paleovirologists who study fossil viruses have found that all viruses share a common single-cell ancestor from more than 3 billion years ago. About 1.5 billion years ago, viruses changed their protein coating, allowing them to penetrate the cells of their hosts. As multicellular life became increasingly complex, viruses got simpler, eventually giving up i...

In earlier episodes, you heard that trillions of viruses live peacefully, even beneficially, within each of us today. And that our ancestors battled now-extinct “fossil viruses,” which are preserved in our own genetic code. Turns out, that’s been beneficial too. For instance, viruses helped drive our evolution. 100 million years ago, proto-mammals were infected with a virus that encoded into their DNA the ability to produce syncytin, a protein that viruses use to fuse cells together so they can ...

Mt. Everest, at just over 29,000 feet above sea level, may be the highest point on Earth’s surface—but what’s the lowest? Well, the deepest part of the deep sea is the Mariana Trench in the Pacific, off the island of Guam, about halfway between Japan and Australia. It’s five times as long as the Grand Canyon and more than a mile deeper than Everest is tall. And the deepest point in the trench is called Challenger Deep, nearly 36,000 feet below sea level. It’s named after the Challenger 1 and 2 e...

In another EarthDate, we talked about Challenger Deep, the deepest point in all the oceans, at almost 7 miles down. The first humans to explore it were a Swiss oceanographer and U.S. Navy Lieutenant. They built a special deepwater submarine called a bathyscaphe, and in 1960, headed for the bottom. It took them 3 hours to reach the western pool of Challenger Deep at 35,000 feet. But they stirred up so much sediment, they couldn’t see anything. That, and a worrisome crack in a window, cut their tr...

You may have heard that bumblebees shouldn’t be able to fly. That’s a myth actually, as any flying bumblebee will tell you. The science of their flight is now understood. But the bees hold another mystery that could affect human agriculture. Bumblebees hibernate over winter, and when they emerge in the spring, they’re hungry. But what if the plants they rely on for pollen and nectar aren’t yet producing? The bees actually force them to do it. Like their honeybee cousins, bumblebees scout their e...

What if you’re a fish in freezing water? Well, a free-swimming ocean fish can migrate to a warmer part of the sea. But if you’re a lake fish, you don’t have that option. Luckily, the properties of water make its solid form—ice—less dense than its liquid form. As a lake freezes, the ice floats on the surface, insulating the water below and keeping most lakes—and the fish within them—from freezing solid. You would still, however, be very cold. Lake fish have to lower their metabolism and enter a s...

The horseshoe crab is a living fossil—sometimes called a stabilomorph, a body design that evolution got so right, it hasn’t had to change. They’ve been roaming the coastal shelves and brackish bays of Earth for more than 400 million years in nearly the identical form as today, having survived all five great extinction events we’ve discussed on EarthDate—including the asteroid that wiped out the dinosaurs. Why are they so enduring? A few reasons: They’re generalists that can live in shallow or de...

Each winter in the Northern Hemisphere, it feels like Earth is drifting farther away from the warmth of the Sun. In fact, it’s just the opposite. When we measure the size of the Sun in our sky, we find that it actually appears 3.4% larger in winter—because it’s 3.4% closer. More than 3 million miles closer. The Sun is about 95 million miles away in summer, but just 92 million in winter. And this is because Earth’s orbit is elliptical, with Earth following the closer part of its path during the n...

You’ve probably heard that no two snowflakes are alike. And mostly, that’s true. Snowflakes aren’t formed from freezing water, but when water vapor freezes, skipping the liquid stage altogether. This allows the water molecules to organize themselves into the snowflake’s delicate structure. Snow crystals come in more than 30 basic shapes, with the classic star-shaped snowflake forming best in temperatures around 5 degrees Fahrenheit. These begin when water vapor freezes around a nucleus like a du...