6 Ways Ancient Earth Was A Hellish Alien Planet
Earth wasn't always the sparkling paradise it is today, with its healthy flourishing wildlife, pristine protected natural expanses, and informed intelligent populace. No, once upon a time (actually many times upon a time), Earth was an otherwordly hellscape, either licked by devilish flames, encased in frost, drenched in acid, or pummeled by supersonic wrecking balls from space.
And the best part about Earth's checkered past? We're learning more about it all the time. Scientists only just recently figured out about the ...
Periods Of Insane Cosmic Violence
Earth has been the subject of devastating planetary bombardment, from its molten infancy to its awkward adolescence and even through its tenure as the solar system’s life supporting-est planet. One such episode of cosmic abuse lasted an entire billion years, from 3.5 to 2.5 billion years ago. During that vast expanse of time, asteroids greater than six miles in diameter routinely struck our planet every 15 million years, a rate 10 times higher than previous estimates. Some of these planet-rattling rocks were the size of cities or provinces and much larger than the Chicxulub impactor 66 million years ago that fortuitously terminated the T. rex.
With moons and other planets, we have their many craters as evidence for past collisions. But Earth's geologic and climatic processes have smoothed over most terrestrial craters, like surgeries smoothing your favorite aging celeb’s pockmarks. Luckily, our wild planet keeps another form of evidence: tiny glass particles formed whenever a sizable cosmic sling-stone smashed Earth. These "spherules" were blown up then rained back down, and their global coverage reveals the severity of the strike.
Turns out there were way more than estimated, involving asteroids many miles across. For reference, here’s Arizona's 50,000-year-old Meteor Crater, formed by a meteorite less than 200 feet across:
But that’s nothing. According to the evidence of gigantic Moon craters, more than 10 miles across, a stupendous space chunk about 60 miles wide (10 times the dinosaur killer) smashed the Earth-Moon system around 800 million years ago. The resultant asteroid shower could have battered our planet with 40-50 trillion metric tons of material.
This stupendous disaster possibly kicked off the Cryogenian period, Earth's 100-million-year-long Ice Age. Then, 470 million years ago, a small meteoroid shower again pelted us and potentially knocked our planet back into the frigid grip of another, smaller Ice Age. So yea, space is cruel and showers us with cosmic hellfire and ice. If you aren't currently frozen or aflame, count your blessings.
Earth Once Had A Venusian Atmosphere
Venus is like Earth's sibling that dropped out of school and did (hard) drugs. The planets are similarly sized, and many eons ago, when the Sun was dimmer, Venus wasn't so infernal. Then the Sun got hotter, Venus belched itself a thick CO2 atmosphere, and it transformed into a 900-degree planetary greenhouse, with sulfur clouds and a crushing atmospheric pressure 90 times greater than Earth. And this could have been our fate, if not for our fortunate distance a bit farther away from the capricious Sun.
Here’s how it went down. Toward the end of Earth's planetary formation, a Mars-sized body smashed through, giving us our Moon. It also turned our planet into a gigantic magma ocean, but hey you can’t make an omelet without breaking a few continents. Scientists recreated this process on a tiny scale to figure out the ancient atmosphere’s composition. They levitated a rocky pellet on a stream of gas then heated it to nearly 3,500 degrees with a laser. Lo and behold, the incandescent gases swirled around this molten marble as they did around the liquefied, pre-pubescent Earth.
Then, researchers matched these gases to the chemical signatures found in the Earth's mantle, to extrapolate the components of the early atmosphere. It was almost identical to the one around Venus, consisting of 97% carbon dioxide and 3% nitrogen, with an atmospheric pressure 70 times greater than today. Luckily, our position in the "Goldilocks zone" allowed the steamy water vapor to cool into oceans, which absorbed CO2 from the atmosphere, while Venus' water remained as vapor, leaving all that heat-trapping CO2 in the air.
The Worst Mass Extinction Ever
Earth was feeling pretty good about itself circa 253 million years ago. Land, sea, and plant life was flourishing at an unprecedented rate. Then, 252 million years ago, came the Permian–Triassic extinction, also charmingly known as “The Great Dying.” It killed more than 70 percent of land species and 96 percent of ocean dwellers.
This worst ever extinction event was a multi-pronged catastrophe of global (and cosmic) proportions, and scientists are constantly finding new ways it sucked. One major cause was Earth's worst volcanic events. Siberia became an erupting field of lava and volcanoes, where violent outbursts continued for at least two million years, spewing enough molten material to cover the entire contiguous U.S. to a depth of nearly a mile.
The ash blocked out sunlight and caused an unseasonably early and hellish winter. Then the oceans acidified and warmed, with equatorial oceanic temperatures reaching 104 degrees. The same occurred on land, where temperatures increased by more than 20 degrees in some regions.
Siberian lava scorched gigantic underground petroleum deposits, filling the air with vaporized oil and coal. But the accursed Siberian lithosphere also held large amounts of chlorine, bromine, and iodine. These elements are insanely deadly as gases and stripped away the protective ozone layer, increasing the extinction's death-dealing potential.
And there's more. As The Great Dying killed off the bottom-feeders that keep algae and aquatic microbial populations in check, these organisms proliferated and caused waves of toxic blooms. They depleted the oxygen and toxified rivers, lakes, and other aqueous bodies, creating a lethal microbial soup that poisoned any creature sipping (or living in) its foul liquid. It wasn't a very fun time for anyone. But would you believe catastrophes like this, at other times, actually helped the Earth? For example ...
Global Acid Storms Helped Melt Iceball Earth
Earth has had at least five Ice Ages. And as hard as it may be to believe based on the recent thigh-sticking temperatures, we're still in an Ice Age. Or, technically, for the past 11,000 years we've been enjoying an "interglacial" period of warmth that separates icier episodes.
But on at least a few occasions, the whole planet was an ice-and-snow-locked Hoth, sans wampas. These "snowball" periods were caused by multiple factors, including plummeting carbon dioxide levels and shifts in Earth's orbit.
Somehow, our resilient planet always pulls itself up, but sometimes it's a lesser of two evils scenario. Case in point, the Marinoan Glaciation of 650-635 million years ago, when ice sheets more than one mile thick stretched from pole to pole. This period was thawed by a nightmarish event: intense greenhouse-gassing that led to worldwide acid rains and floods.
Though the Marinoan Earth's frozen surface resembled a Snow Miser wet-dream, geologically flatulent processes beneath the icy shell pumped out vast amounts of carbon dioxide. CO2 concentration reached a level 500 times greater than today, melting many millions years' worth of ice in just 2,000 years. This outrageous output was accompanied by global storms that bathed the defrosting planet in acid for hundreds of thousands of years. And with the caustic torrents came catastrophic floods that washed over every continent.
Counterintuitively, we may owe our existence to the event. It consumed 99% of the CO2 in the air and eroded and washed rocks into the seas, de-acidifying the oceans and possibly providing a mix of minerals. These minerals spurred the "Cambrian explosion" of 540(ish) million years ago, when sophisticated life forms rapidly evolved and went on to inhabit every part of the planet except New Jersey.
In 1859, the Sun bombarded us with what was thought, until recently, to be the pinnacle of solar flares. It overloaded the planet's magnetic field and sparked a geomagnetic storm, setting telegraph wires ablaze and causing gnarly auroral displays. Old-timey people probably attributed it to witchcraft and devilry and, well, we don't blame them.
Today, such an outburst could disable undersea cables and take down the internet, potentially for months, costing the U.S. $7 billion per day in lost lolcat ad revenue. And now, scientists are freaking us out by saying that these flares are more common, and more potent, than given credit for. We've been underestimating Sol this whole time, and a good solar flare can release energies 10 to 100 times that of the 1859 Carrington Event.
Researchers found evidence of at least three of these disaster movie megaflares within the last 10,000 years. Tree ring data holds evidence of such cosmic catastrophes, as do ancient air samples trapped in ice cores, which contain flare-ified isotopes of beryllium and chlorine. They all agree that solar flares hit us hard.
Here’s why that sucks. Solar flares, like a relatively piddly one in 1989 that plunged Quebec in darkness, carry their own magnetic fields, which induce electric currents under the Earth's surface and overload our electronics. And that flare was much weaker than the Carrington Event, which was in turn so weak relative to megaflares that it doesn't even register in tree ring data.
A real whopper of a flare, as occurred in AD 774, is like the Sun ejaculating 100 billion megatons of nukes. If we could harness it, that would power our civilization for 300,000 years or mine dozens of Dogecoin. But we couldn't harness it. It would instead zap satellites, cause massive power outages, and irradiate airplane passengers with a lifetime dose in just a few hours.
But the severity of truly super-duper-megaflare is unknown. They're so much stronger than what was thought possible that researchers have never simulated such an event. Sure, it would knock out the internet and other technologies, but it could also completely wipe even more stable stuff, like every electronic record. It might delete every single photo of when you were 17, so really, it won't be all bad.
Earth Was Literally Waterworld
We used to think the overall size of the seas hasn't changed much since the early eons. But recent studies suggest the ancient oceans (or one giant ocean) may have been nearly twice as big. This would have covered almost the entire, and possibly the entire, planet during the Archean period (circa 4 to 2.5 billion years ago).
Where did all the water go? Into the rocky, mineral-rich mantle, which sits just below the Earth's (relatively) apple peel-thin crust. The mantle was once warmer, which reduced its water-holding capacity, with the extra aqua pooling on and covering an overwhelming majority of the surface.
A Harvard study came up with that, and a separate study scrutinized a particular oxygen isotope that normally gets sucked out of the water by continental landmasses. And, yep, this study agreed: looks like the Earth was a wet world about three billion years ago. However, as in Waterworld, the early Earth may have featured at least a little bit of land. These rare, scattered terrestrial havens were probably nothing more than rocky islets jutting out of the thalassophobia-inspiring Neptunian depths.
And yet these shreds of land may have harbored simple organisms. If we've learned anything from those viral photos of mushrooms sprouting from suspiciously moist towels, it's that life finds a way.