5 Strange Things You (Probably) Didn't Know About Earth

The Planet’s Poles Flip

We all know that North is, well, north—somewhere above Alaska—and south is down near the middle of Antarctica. That will always be true for the planet’s geographic poles, but it’s only intermittently true for the planet’s magnetic poles. Over the past 20 million years, the magnetic poles have flip-flopped every several hundred thousand years or so, which means that if you had a compass in hand about 800,000 years ago, it would tell you that north was in Antarctica.

Though scientists are pretty sure Earth’s churning, molten iron core powers these polar acrobatics, it’s not entirely clear what triggers the actual reversals. The process is gradual and occurs over millennia. For now, Earth’s north magnetic pole is creeping northward by about 40 miles a year. And given that the last major pole reversal happened 780,000 years ago, we are overdue for a flip.

It Has a Supersized Moon

Sunday evening marked the most recent rising of the supermoon, but regardless of how large Earth’s moon appears in the sky on any given night, it’s always among the solar system’s most overgrown satellites. Relative to Earth, it’s positively enormous, coming in at a quarter as wide as our home planet.

The only celestial twosome that bests the Earth-moon team in this regard is Pluto and its biggest moon Charon, which really form more of a binary system—a pair of objects twirling around each other—rather than a typical planet-moon pair. And thank goodness the moon is so big and so close. If it were smaller or farther away, we would never see total solar eclipses.

The Biggest Mammal Migration Is Airborne

Yep, you may have thought the 1.3 million wildebeest that hoof their way between Kenya and Tanzania were tops, but you’d be wrong.

Millions and millions of bats—giant fruit bats, to be exact—fly between the Democratic Republic of Congo and Zambia’s Kasanka National Parkeach year. With more than 10 million of these cat-size, mango-munching, echolocating chiropterans involved, it’s the largest known mammal migration on Earth.

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It Hosts a Humongous Fungus

When it comes to the biggest living things on Earth, it might be easy to think about blue whales, elephants, and trees. You may even recall that coral reefs are the largest conglomerates of critters.

But largest single organism reported is an Armillaria mushroom in Oregon. In 1992, one of these fungi was found in Michigan covering 37 acres. But more recently, teams investigating a mysterious tree die-off found that the culprit was an even more monstrous fungus, covering at least 2,000 acres and estimated to be thousands of years old.

Though the mushrooms themselves erupt out of the soil, they’re connected by a tentacular underground network of tissues called mycelia. There’s a chance the mushroom’s offshoots may not all be perfect clones, but it does appear as though the giant fungus takes this particular trophy (and it apparently tastes great with spaghetti).

There’s an Underwater Meadow

Who is the oldest of them all?

The Mediterranean’s most widespread seagrass, namedPosidonia, after the Greek god Poseidon, is also thought be among the oldest known living things on Earth: Genetic sequencing recently revealed that an expansive Posidoniameadow growing off the coast of Spain could be as many as a hundred thousand years old.

This means that before our modern human ancestorseven left Africa, the first of these seagrass shoots was gently putting down roots and beginning a process of cell division and cloning that would survive through the global spread of humankind. One of the reasons that slow-growing Posidonia can last for so long is that it has few natural competitors or predators—except for humans, whose exploding populations and poor habitat management are slowly destroying the ancient meadows.

One River Is Boiling

Once thought to be the simple stuff of legend, a boiling river hidden deep in the Peruvian Amazon actually exists. OK, it’s not actually boiling, but the river comes within a few degrees of that mark, and it’s still hot enough to transform an already otherworldly rain forest into a steaming, mystical paradise that can cook clumsy small animals alive.

Recently, National Geographic explorer Andrés Ruzo went to the boiling river and returned with a reason for its effervescence: tremendous geothermal activity that’s unrelated to volcanoes or oil-drilling.