ONE STRANGE ROCK
There’s no doubt that planet Earth is awe-inspiring. That’s even more true for the handful of humans who’ve seen it from space with their own eyes.
“We tend to think of ourselves as a weird, tiny little human being on a very large, powerful planet, and therefore clearly irrelevant to anything that might affect the planet at a planetary scale,” says former NASA astronaut Kathryn Sullivan, who in 1984 became the first U.S. woman to walk in space. “In some ways that’s true. But if you step back and look at the planet in total, you see how richly interconnected and intertwined all the actual systems are.”
Even with all its magnificence and majesty, Earth is also just kind of strange. Aside from the fact that it’s the only planet known (so far) to support life, it has a bunch of inherent quirks, from geophysical weirdness to the landscapes adorning its surface to the organisms it supports. And the more we learn about Earth’s peculiarities, the more we grow to appreciate and treasure its many wonders—starting with the air we breathe.
“You look back at the Earth and that huge majestic ocean, [the atmosphere is] a lot more like the fuzz on a tennis ball than some big massive thing,” Sullivan says. “It’s like the wall of a soap bubble, this little membrane that envelops this grain of rock and is the reason that critters like us can live.”
Here are some of the oddest things about this gas-shrouded ball of water and rock we call home.
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 Park each year. With more than 10 million of these cat-size, mango-munching, echolocating chiropterans involved, it’s the largest known mammal migration on Earth.
Bats on the Wing
A Mexican free-tailed bat comes in for a close-up as it leaves its cave to hunt. Every night from March to October, 1.5 million of these bats stream out from beneath a bridge in downtown Austin, Texas.
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).
Some Parts Are Downright Alien-Looking
Ethiopia’s Danakil Depression is a bizarre landscape worthy of the superlatives tossed at it. Hottest. Driest. Lowest. Weirdest. Though simmering hot springs, poisonous gases, crackling lava lakes, and salty mirages make the Danakil Depression seem like one of the most inhospitable places on Earth, even here, life has found a way. Multicolored hydrothermal vents are home to ecosystems that astrobiologists are now using as analog in the search for life beyond Earth.
One Island Boasts an “Undersea Waterfall”
The southwest coast of Mauritius appears to be teetering on the edge of a plunging, undersea waterfall. But the looming abyss, and the island’s precarious position, are just an illusion. Swirling ocean currents carrying silt and sand create the forbidding pattern, which is painted atop a relatively innocuous seafloor. It’s quite spectacular when viewed from above and can even be seen in Google Earth imagery.
There Are Hidden Gems Beneath Your Feet
Buried a thousand feet underground, the gypsum pillars in Mexico’s appropriately named Cave of Crystals are the largest natural crystals known. Some of the beams in the sweltering cave measure more than 30 feet long. You might think it hard for Earth to hide such a glittering crystalline trove, but the cave was only discovered in 2000, when silver miners accidentally broke through its walls.
A similarly magical subterranean treasure, Vietnam’s Hang Son Doong cave—the world’s largest—also remained hidden until relatively recently. Spotted in 1991, the cave hosts a lush rain forest and is big enough for a 747 jumbo jet to comfortably park inside.
Some of Its Clouds Are Alive
Sometimes, at dusk, dark shape-shifting clouds appear near the ground. As they swirl and morph, these clouds can seem positively alive—and it’s because they are. Formed by hundreds or thousands of starlings flying in tandem, the phenomenon is known as a murmuration. Scientists suspect the birds engage in this mesmerizing display when they’re looking for a spot to roost or evading predators. But it’s still a puzzle as to how, exactly, they achieve such exquisite acrobatic synchrony on the fly.
There’s an Underwater Meadow
Who is the oldest of them all?
The Mediterranean’s most widespread seagrass, named Posidonia, after the Greek god Poseidon, is also thought be among the oldest known living things on Earth: Genetic sequencing recently revealed that an expansive Posidonia meadow growing off the coast of Spain could be as many as a hundred thousand years old.
This means that before our modern human ancestors even 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.