Episodes

  • Making the Invisible Visible

    Making the Invisible Visible
    Mar 26 2026
    In a previous EarthDate, we told you about the accidental discovery of X-rays in the late 1800s. Scientists around the world began to experiment with them. Thinking them no more harmful than visible light, they did so without protection… sometimes with disastrous results. Early researchers would place the emitter in the center of the room, hold up their hands, and—using special lenses to examine their bones—looking directly into the beam. One of Edison’s scientists absorbed enough X-rays to develop severe skin cancer, which killed him. Non-scientists around the world went to demonstrations and submitted themselves to high doses. In the 1930’s, shoe stores used X-rays to fit their customers’ feet, a practice that endured, remarkably, till 1950. By then, X-rays were more completely understood, both for their incredible potential and their potential danger. Since then, their medical use has safely expanded to include sophisticated 3D imaging and highly targeted beams to destroy cancer cells. Beyond airport scanners, X-rays are now used to examine concrete structures for defects, to authenticate rare paintings, and to study the atomic structure of mineral crystals. NASA used similar technology on its rovers to analyze Martian soil and gathers X-ray data from space using orbiting telescopes. Revealing the inner secrets of celestial bodies and our own, this accidental discovery continues to make the invisible visible.
    Show more Show less
    2 mins
  • 125 Years of X-Rays

    125 Years of X-Rays
    Mar 26 2026
    X-rays are common today, but their accidental discovery 125 years ago was celebrated around the world as a scientific miracle and earned Wilhelm Röntgen the first Nobel Prize in physics. Röntgen was working in his lab in Germany, trying to replicate the experiments of other scientists with an electrified cathode tube, when he noticed some barium-painted cardboard nearby fluorescing. Puzzled, he turned off the lights, but it continued to glow. He realized the cathode tube was emitting something other than light. When he went to move the barium board, he noticed a lead plate cast a shadow on it. He began to try to create images, placing objects between the tube and the cardboard. He realized the mysterious rays were penetrating soft objects but not hard, and was shocked to see, in one image, what looked like the bones of his hand! Recognizing the potential, he tried to capture a clearer image of bones. He finally produced one of his wife’s hand and published it in an article. Not knowing what the rays were, he named them after the mathematical unknown, “x.” Worldwide acclaim was swift. Within a month, he was called in front of Kaiser Wilhelm to demonstrate and awarded a prestigious medal on the spot. Within a year, doctors in the Balkan war were using X-rays to find bullets and broken bones, and scientists the world over were experimenting with them… without understanding their risks. But that’s a story for another EarthDate.
    Show more Show less
    2 mins
  • Creepy Corpse Flowers

    Creepy Corpse Flowers
    Mar 25 2026
    Wondering what to get that special someone for Halloween? How about a bouquet of corpse flowers? Of course, you’ll have to go all the way to Indonesia to get them. And it would be a very, very large arrangement. There are two types of corpse flowers, and both emit a strong odor of rotting meat to attract flies and beetles to pollinate them. Titan arum lives up to its name, with flowers topping 10 feet in height. To produce a bloom of such staggering proportions, it spends a few years as a small tree with wide sun-gathering leaves, storing energy in a giant tuber that could weigh 200 pounds. When the tuber is ready, the tree dies to the ground. Then, rising as if from a grave, a large, solitary shoot breaks the earth, growing 3 inches a day, then finally unfolding its petals like a cloak to reveal the largest, stinkiest flower in the world. The other, very different corpse flower, fittingly, is a parasite. It attaches itself to vines in the jungle, where the body of the plant lives within them, drawing all its water and nutrients from the host. Then, once in a blue moon, it will produce a huge, red, stinky, platter-shaped bloom on the forest floor—the widest and heaviest flower in the world, at nearly 4 feet across and more than 25 pounds. These denizens of the botanical underworld may not smell very good, but their spectacular appearances are a frightfully memorable sight.
    Show more Show less
    2 mins
  • How Do Animals Vote?

    How Do Animals Vote?
    Mar 25 2026
    They may not go into polling booths and come out with an ‘I Voted’ sticker. But most animals that live in groups have developed ways to make collective decisions and act together for the good of one and all. English rock ants are always scouting for a new nest. When a few individuals find the same new spot, they seem to agree that this real estate has potential. So they go back to the current nest to try to lead other ants over, one by one. If they can persuade enough to follow, they’ll hit a critical mass at the new place, and the decision is made: this is now home. The ants don’t wait for others to share their opinion. They go back to the old nest, pick up the stragglers, and carry them over. Meerkats depend on the group for survival, so maintaining social cohesion is vital. Each morning, they go out foraging for bugs and plants in a widely spaced mob. When one of them has completely explored its own small area, it will call out to the others. Once three meerkats vote for a move in this way, the group will set out together for the next place. Roving baboons, like us, are more political animals. When two or more set off in different directions, the troop will choose a path that’s halfway between them. The fringe elements will eventually drift back to join the middle; they may not have gotten exactly what they wanted, but they can be satisfied they had a say in the group’s decision. Examples of consensus, communication, and compromise that perhaps we humans can learn something from.
    Show more Show less
    2 mins
  • Anoles Get a Grip

    Anoles Get a Grip
    Mar 25 2026
    Earlier, you heard how geckos have a sticky superpower. Microscopic hairs on their toes generate electromagnetic attraction to the surfaces they walk on, letting them run up glass and across ceilings. Anoles—common garden lizards in the southern U.S.—have less stick. They can dash up trees but can’t cling to the underside of things. Their electromagnetic attraction evolved separately from geckos’. In fact, they diverged on their family tree more than 200 million years ago, before either developed this capability. And both are still evolving. Evolution happens when individuals with certain characteristics can outcompete others in their species—for food, territory, or mates—allowing them to pass on those advantageous qualities. Recently, in the Caribbean, island anoles with larger toe pads gained an advantage when hurricanes literally blew away their competition: anoles with small toe pads and less staying power. The larger-toe-pad anoles held fast and lived to breed another day. And within just a few years, the entire population had evolved to have bigger, stickier feet. A few islands over, anoles in Puerto Rico also developed larger toe pads in response to urbanization. Their man-made climbing surfaces are slipperier than in the jungle, and the stickier anoles could better survive, thrive, and breed. Perhaps it’s this remarkable adaptability that has allowed anoles to stick around so long.
    Show more Show less
    2 mins
  • Hanging with Geckos

    Hanging with Geckos
    Mar 24 2026
    Have you ever seen a gecko walk straight up a glass door, or sprint upside down across a ceiling, and wonder, “How can they do that?” To get the answer, you’d need an electron microscope. At 200× magnification, you’d see the gecko’s toes are covered with tiny hairs called setae. Zoom in closer and at 1000×, you’d see that the setae are actually bunches of hairs, like in a hairbrush. Much closer, at 55,000×, you’d see that each one of those hairs splits again into hundreds of branches of spatulae, shaped like spatulas. The spatulae are thinner than a wavelength of visible light—so small they can get close enough to the surface the gecko is walking on that electrons in the spatula and surface material begin to pull on each other. The force on just one spatula is weak. But multiplied by the 2 million spatulae on a gecko’s toe, it’s strong enough to hold the gecko onto glass using just that one toe. When it needs to move, the gecko flexes muscles in its toes to change the orientation of the setae, turning its foot from sticky to not in an instant. It can coordinate these on–off movements with every step, every fraction of a second, to run up a wall or across a ceiling without falling. Scientists have been trying to emulate this incredible, controllable, atomic-level stickiness, but so far, the gecko has us beat… up, down, and sideways.
    Show more Show less
    2 mins
  • Copper’s Superpower

    Copper’s Superpower
    Mar 24 2026
    Phoenician soldiers, when injured in battle, would shave bronze from their swords into their wounds. Why? For the copper. Copper is often found in its pure state, rather than bound in ore, and is easy to bend. This made copper the first metal to be shaped by humans into useful implements around 10,000 years ago. The Copper Age lasted 5,000 years, until someone realized they could add tin to copper to make bronze, which was easier to melt and cast, harder as a finished product, and better for tools and weapons like Phoenician swords. Those soldiers and their contemporaries knew that copper is antimicrobial. High-copper alloys, like bronze, preserve that attribute. Egyptian doctors used copper to disinfect. Anatolian mothers fed babies from copper cups, since it killed the germs that caused diarrhea. Modern researchers have finally caught on, and for the past 20 years have studied copper’s antimicrobial effects. The process is still not completely understood, but when microbes—including the coronavirus—land on copper, it releases charged particles that invade the microbe, disrupt its DNA, and kill it within hours, even minutes. Studies have found that hospitals can reduce infections by up to 10 times by replacing plastic and stainless steel with copper alloys, and many have begun to use them for high-touch surfaces. The future of healthcare may benefit from the ancient properties of copper.
    Show more Show less
    2 mins
  • Riding the Jet Streak

    Riding the Jet Streak
    Mar 23 2026
    When passengers boarded a British Airways flight from New York to London on February 8, 2020, they had no idea they were about to make history. Once their 747 reached cruising altitude, the pilots directed the plane into a jet streak, a fast-moving current of air that sometimes occurs in winter. The streak rocketed the plane to a ground speed of 825 miles an hour, cutting travel time by 25 percent and setting a record for subsonic aircraft making the trip. The surprised passengers arrived in London in less than 5 hours—an hour and 40 minutes ahead of schedule. One hundred EarthDate episodes ago we talked about the jet stream, the west-to-east currents of air that circle the globe. It’s common in winter for the Northern Polar Jet to drift southward into what pilots call the North Atlantic Tracks, the routes they fly from the U.S. to Europe. When other factors, like a storm system, increase its velocity, the jet stream can create jet streaks—rivers of wind more than twice as fast, at up to 250 miles an hour, like the one that carried that February 2020 flight. Faster trips like these save time and fuel and reduce exposure to cosmic radiation for passengers and crew, which happens on any flight. So, if you’re looking for a quick, efficient, safe trip to Europe—and your own chance to land in the record books—plan one for a stormy winter night… but don’t plan to sleep!
    Show more Show less
    2 mins