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EarthDate

EarthDate

By: Switch Energy Alliance
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 EarthDate is a short-format weekly audio program delivering concise, science-based stories about the Earth: its geology, environments, and the processes that shape our planet over deep time and today. Beginning in 2026, EarthDate is managed by Switch Energy Alliance and hosted by SEA's founder Dr. Scott W. Tinker. Together, we explore earth systems, natural resources, and their relevance to everyday life, with a focus on clear, accessible science education for broad audiences. EarthDate is written and directed by Emmy-winning filmmaker Harry Lynch, and researched by Lynn Kistler. We search for captivating stories to remind listeners that science can enlighten, educate and entertain.Copyright 2026 EarthDate
Episodes
  • Triple North Pole

    Triple North Pole
    Mar 2 2026
    It might surprise you to know there are actually three North Poles: the geographic, the magnetic, and the geomagnetic. The one we most commonly think about is the Geographic North Pole—the tip of the axis that the globe spins around. It’s in the middle of the Arctic Sea, on pack ice, above more than 2 miles of water. During the summer, when the pole is tilted toward the sun, it’s 24-hour daylight. In the fall, the sun finally sets—once, and only once, per year. That brings on 6 months of night, until springtime, when the once-annual sunrise starts another 6 months of day. The North Magnetic Pole is slightly to the south. This is where Earth’s magnetic field, which springs out of the ground at the South Magnetic Pole, dives back into the ground. Its exact location, however, is constantly changing, because Earth’s magnetic field is always changing. Today, magnetic north is moving about 34 miles a year, gradually traveling toward Siberia. Finally, there’s the North Geomagnetic Pole—the northern axis of the magnetosphere, the magnetic shield that protects us from solar winds. If you imagine the magnetosphere as a ball around a bar magnet, with the bar running through Earth, this pole would be the positive end. It’s currently 700 miles south of the Geographic North Pole but also always traveling. With three dark places to look in the dead of winter, and two of them moving, it’s a wonder Santa ever makes it home.
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    2 mins
  • Carving a Canyon

    Carving a Canyon
    Mar 2 2026
    The Grand Canyon is so grand it can be seen from space. At more than a mile deep and nearly 300 miles long, it could hold all the world’s river water and still be only half full. And its colossal size is an evolving mystery. Early geologists could not believe such a comparatively small river could carve something so immense. So they looked more closely… And discovered that a myriad of geological processes have combined to form the canyon through time. One of the more dramatic is giant floods, vastly larger than anything we see today. Floods from melting ice sheets. From enormous lakes overflowing their boundaries. From lava dams forming within the canyon, which held back water until they failed spectacularly. Floodwaters can carry hundreds of times more rock material than a normally flowing river. These superfloods likely dragged house-sized boulders through the canyon, battering the softer lower rock layers until they collapsed, bringing all the rock above them crashing down, to be carried away in the next superflood. Geologists suspect these processes happened repeatedly in several smaller canyons, which finally linked together to become the Grand Canyon we know today. In 1919, the U.S. Congress and President Woodrow Wilson set aside the canyon as a National Park for, as Theodore Roosevelt had said years earlier, “your children, your children’s children, and all who come after you.” If you haven’t seen it with your own eyes, you owe it to yourself to go and be awed by the Grand Canyon.
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    2 mins
  • Homing Pigeons

    Homing Pigeons
    Mar 2 2026
    Since the Roman Empire, troops have used homing pigeons to carry messages from the front lines to command posts. They remained popular for long-distance communication, even after the telegraph was invented in 1844. In World Wars I and II, homing pigeons could operate faster than wires could be strung and farther than the troops’ radio signals. In one famous account, an infantry unit trapped behind enemy lines released three pigeons, but all were shot down. Despite her injuries, one took flight again and successfully delivered her message to save the soldiers. Military surgeons were able to save her life, and she received a French medal of honor and a visit from U.S. General John Pershing. Long ago, homing pigeons were bred from normal rock pigeons, which could find their home from as far as 1,000 miles away. Eventually, handlers realized they could train them to fly between points, by putting their feed at both spots. The birds could even adapt if one of those locations moved. This remarkable power of navigation is partly based on magnetoreception, as we discussed in an earlier EarthDate. But they may also be following anomalies in Earth’s gravitational field, infrasonic sound waves, and scent trails in the atmosphere. The only sense they use that we can experience ourselves is visual. Some studies suggest the birds read surface landmarks like rivers and highways to build their own aerial maps as they fly. It’s yet another remarkable adaptation of life.
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