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The 10 Biggest Cosmic Catastrophes That Could Wipe Out Life on Earth Tomorrow

What is the most dangerous cosmic threat to the humankind?

By What IfPublished 3 years ago 12 min read
Artist's conception by Vadim Sadowski

Let’s say, for a moment, that humans don’t wipe each other out with some kind of nuclear war or via climate change. Let’s say we get our stuff together and find some kind of peace and harmony to leave for future generations. Sounds pretty good, right?

That doesn’t mean the Universe won’t have it out for the mere mortal inhabitants of Earth. There are still plenty of galactic issues that could lead to this planet’s downfall and demise.

10. Death by Asteroid?

Our planet gets hit by about 100 tons of dust and sand on a daily basis and an asteroid the size of a car comes into our atmosphere at least once a year, but the friction from our atmosphere burns it up. But the biggest factor isn’t size — it’s location. Most asteroids hit oceans or forests, but a 100-meter-long (328 feet) rock, big enough to withstand the friction from our atmosphere, hurtling toward Earth at a speed of 30 kilometers (19 miles) per second would take mere seconds to rip through all the layers of our atmosphere and, if it hit New York City, it would instantly kill 2.5 million people. The ensuing fireball would destroy everything in a 3-kilometer (1.8-mile) radius; the extent of the immediate damage would spread out in a 7-kilometer (4.5-mile) radius from the impact zone.

There’s also the risk of radiation damage (assuming the space rock contains the stuff). But if the asteroid were bigger? Like a 10 kilometer-wide (6 mile) rock, which would seriously mess things up just by making contact. We’re talking a seismic wave so big, it’s likely most of Earth’s inhabitants would be killed just about instantly. The dust from the impact would cover the world, block out the Sun and, despite taking about a year to settle, even if people did survive, there wouldn’t be much food left for those who resurfaced.

9. Gamma Gamma Ray! No!

Consider a gamma-ray burst (GRB) instead. A GRB is the Universe’s equivalent of a wrecking ball with pinpoint accuracy. A direct hit on Earth would basically be a reset of everything here, wiping out all life (human, plant and animal) really fast. GRBs are the highest energetic form of life, hundreds of times brighter than a supernova with the potential to be even more powerful — we’re talking a million trillion times brighter than our Sun. They can last between a few milliseconds to a few minutes, but mere seconds is all that would be needed to fry up all life on Earth. GRBs are caused by the creation of supernovas or when a black hole swallows a neutron star.

It’s possible humans could make it out alive, depending on where it originated. If it came from 3,000 light-years away, the blast would be absorbed by the Earth but our satellites would be knocked offline. If it were closer, like 500 light-years away, the radiation would destroy the ozone, killing the plants and therefore most of our food supply AND our oxygen. We’re talking starvation and suffocation for humans and animals. If the GRB came from a closer distance? Say goodnight, Gracie: our atmosphere would be destroyed instantly. The good news? We’re not in any immediate danger of being fried in our homes.

8. One Rogue Planet is More than Enough

Wandering planets, untethered by a star like our Sun, could decide to take a joyride and mess up Earth’s orbit, along with those of our celestial neighbors. There’s one about 20 light-years away from Earth, about 17,000 times bigger than our humble Pale Blue Dot. It also has some really awesome auroras, courtesy of its incredibly strong magnetic field. If it found a way to our Solar System, things could get bumpy as it would be moving at hundreds of kilometers per second. If it hit, directly, or interrupted Earth’s orbit, Earth would be a thing of the past.

Working in our favor, however, is that our Solar System is pretty big. But don’t get too excited or sigh with much relief. Instead of a direct hit, we’re more likely to see the planetary orbits messed up, given the rogue planet’s gravitational pull. The orbits would be more elliptical, possibly throwing Earth out of the Goldilocks Zone and possibly making our environment too hot or too cold to support life.

7. No Shelter From This Massive Solar Storm

Yes, the Sun is far. Yes, solar flares look really cool when you see them through telescopes. But coronal mass ejections (CMEs) are not cool at all in real life. In 1859, a CME ignited telegraph pylons on Earth, eliminating communication methods around the globe. A CME in 2012 went through our orbit but didn’t cause any damage. If we were to get hit with another storm now, there would be an electromagnetic pulse hitting Earth’s outer atmosphere, blocking radio signals between Earth and our satellites as a stream of charged particles hit our magnetosphere. So long cell phones, GPS and TV signals!

Within a few days, things would get worse, as those super-charged particles would kind of congeal and form a plasma cloud that would reach Earth. It would wipe out satellites that would normally warn us about such dangers, but we’d still only have about 30 minutes before a geomagnetic storm would hit. On the ground, our power grid transformers would start to melt, causing an international power outage. All our electronics would be useless — even our toilets wouldn’t be able to flush, as water systems are controlled by electricity and computers. There’s really not much we could do to avoid it. Right now, NASA can give us a three-day warning to try and protect our electronics, but that’s the only thing we could really do.

6. There Goes the Sun...

We all know that the Sun is the most important component for life on Earth, to say nothing of keeping our Solar System in order and operating “normally”, from our perspective. If it went away? Yikes. If the Sun exploded, there would be a huge problem to deal with, but we probably wouldn’t have much time to address it. It would take eight minutes for the light from the Sun to stop. Forever. Not only that, but if the Sun were to explode, there would be a shockwave strong enough to boil away half of the planet instantly. The other half would experience a, um, slight temperature uptick to 15 times hotter than the current surface of the Sun. Everything would also go dark.

Earth would also be rudderless, floating off its established orbit, at least for a while, until it found another star in which to fall into a new home, but that would take a very long time. The option for people on Earth as this happened, in the interim, might be to build a network of bunkers under the surface, where the temperature remains a steady 17 degrees Celsius (63 degrees Fahrenheit). We’d need a long warning for this to be successful, of course. But even then, after 1,000 years, surface-level Earth would be frozen from the top down and uninhabitable.

5. A Quasi-Star Would Be A Full-On Disaster

Powered by black holes, quasi-stars are machines of self-destruction. They are much larger than our Sun, measuring about 10 billion kilometers (6.2 billion miles) in diameter, compared with a paltry 1.3 million kilometers (808 thousand miles) around. That’s 7,000 times larger! As it heads toward Earth, and our Solar System, we’d first see an incredibly bright light in our night sky, at least 100,000 as bright as our Sun. The closer it gets, the brighter life would appear here...but it would also send off a tremendous amount of heat.

Other planets and asteroids would be thrown off their orbits, creating asteroids and meteor showers beyond anything we’ve seen. That is, unless the quasi-star ate them instead. Eventually, upon approaching Earth, it kind of wouldn’t matter because we’d all be baked to death, but after hitting 260 degrees C (500 degrees F), the atmosphere would be nothing but steam and carbon dioxide that would later turn to sulfur dioxide. After a while, the crust and mantle of the Earth would vaporize. By that point, there’s no Earth to speak of.

4. Hungry Black Holes Are No Fun For Anyone

Credit: European Southern Observatory (ESO)

Remember that black holes are much more massive than the Sun, and far more powerful. Get too close to one and you’d be ripped apart like spaghetti, one big looooong string of particles. Supermassive black holes are found in the middle of galaxies and stretch about as big as our Solar System, but one black hole in particular, J2157, is the biggest one in the known Universe. It’s about as big as the distance between the Sun and Neptune, times 22. It also has the distinction of being the hungriest black hole on astronomers’ radar. It eats the equivalent matter of one of our Sun per day. If it were to appear in our celestial neighborhood, taking place of the supermassive black hole in the middle of our galaxy, it would be 10 times brighter than our full Moon right off the bat and would outshine most of our regular stars.

A smaller black hole would slowly pull the Sun apart until it was just a cloud of gas. This would unleash a tremendous amount of cosmic radiation. If J2157 came calling, it would eat the Sun whole. Those of us unfortunate to be on Earth at the time wouldn’t be here for long, as the planet might be torn apart by tidal forces. Or it might be attacked with cosmic radiation, or it could be blipped out of existence, with the rest of the Solar System, after being sucked into its center. But take comfort in knowing it is 12.5 billion light-years away and isn’t likely to crash the party anytime soon.

3. Cowabunga! Gravitational Waves Would Lead to an Earthly Wipeout

The result of two black holes colliding, gravitational waves can cause serious damage. Among other things, it would distort gravity! This all ties back to Einstein’s theory of relativity, suggesting that a disruption in spacetime can curve in relation to the energy and momentum of matter and radiation present in its vicinity. Gravitational waves, whether from the collision of black holes or remnants of the Big Bang, travel at the speed of light. The good news is, that means any gravitational waves generated by a crash between black holes might dissipate by the time they reached Earth. But if that happened closer, like in our Solar System, it could wreak havoc, not just in the tangible world but also in the invisible scientific one.

For instance, a strong gravitational wave in our celestial neighborhood could be enough to warp Earth right into oblivion, squeezing and compressing one side of the planet while expanding the other. Imagine massive earthquakes all around the globe at the same time, or incredible volcanic eruptions caused by the sudden increase in pressure as the Earth is squished. The planet would actually change shape, looking more like Io, one of Jupiter’s moons, shifting to a non-spherical entity as it wobbled through the Solar System. All this increased pressure would eventually lead to a real-life game of “the floor is lava”, but it would be real. That’s pretty unpleasant.

2. The Big Rip? RIP Us.

If the Big Bang is what created our Universe, the Big Rip is the logical finale, when all that has been established is destroyed. It will literally tear apart the fabric of the Universe, atom by atom, over the course of a billion years, give or take. Dark energy, which currently makes the Universe expand, would change into phantom energy and, if it grows faster than the Universe expands, POP! Everything we’ve ever known, from our planets to the stars we like to look at, would be done. A person looking through a telescope would see galaxies and planets disappearing as it approached Earth until there’s nothing but a void. Absolute, actual nothing. Eventually, this means Earth will get blinked out too, getting ripped to shreds.

First the surface temperature would drop, as Earth is ripped away from the Sun, which is also being pulled apart at the seams. As the splitting continued, Earth’s crust would crumble, leaving nothing on which buildings could stand. That releases everything from inside the Earth, including more lava, but by this point there’s so much destruction happening so quickly it won’t matter to you, because you’ll be a former person. Croaked. And probably in the middle of being ripped apart, almost like being on the edge of a black hole, without moving an inch. But, hey, don’t worry about it. The Sun is likely to explode before the Big Rip brings the Universe to its natural end.

1. A Planetary Crash - Whose Insurance Covers That?!

We’re lucky that Earth sticks to its celestial lane thanks to the Sun and gravity and the natural order of things. But if another planet were to come into our galactic space we’d know something was off because a weird new celestial body would appear in our sky. It would appear gradually, and our satellites would report the intruder, but there isn’t much we could do about it. There would be impending doom for a while. The planet would actually be approaching at a speed of about 11 kilometers (7 miles) per second, but nothing would be felt on Earth until the planet approaches the Moon. Then, tides here would be eight times bigger, thanks to the new gravitational pull, causing coastline floods.

A day before the planet hits Earth, the new planet would hit a speed of 60 kilometers (37 miles) per second, as the gravitational pull of each celestial body acts like a kind of magnet, drawing the two planets together faster. Now we’d have mega-tsunamis, insane lightning storms, hurricanes and tornadoes all over the world. With just minutes left, the stray planet would hit Earth’s atmosphere, and anyone who wasn’t killed in the horrible weather would see the stray planet’s surface quickly approaching ours. This impending collision also means the two atmospheres are colliding, with friction heating up the air and creating a glow. The surface of the Earth about to be hit would vaporize from the heat and pressure. The other side of the Earth would melt to magma.

The good news is, we have great networks of satellites in low Earth orbit, monitoring for any kind of space invaders. We can’t do anything about an impending collision, at least not right now, but we’d have time to make our peace with the inevitable heat death of the Earth. That’s something...right?

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