How life on Earth could end – sun expanding, rogue planets, robot riots and the ‘Big Rip’

Had a bad day? Don’t worry, it’s not the end of the world – or at least not quite yet.

Earlier this month, a doomsday climate change report warned of a “devastating” future of heatwaves and drought.

The stark climate crisis paper from the UN revealed a humanity-threatening rise in temperatures – following “unequivocal” evidence human activity is warming the planet.

With wildfires sweeping across the world in recent weeks, including devastating blazes in Greece and California, there’s no denying that the consequences of global warming are already being felt across the globe.

And in the worse case scenario, soaring temperatures could not only bake the earth to a crisp, but also lead to rising ocean levels that could leave entire cities underwater.

But what other disasters could usher in the apocalypse? From massive asteroids to black holes and a Terminator-style AI uprising, here is how life on Earth could come to an unwelcome end.

Supermassive black holes

Our galaxy is full of black holes, formed when giant stars collapse in on themselves, and whose gravity is so strong they swallow everything, even the light that may betray their presence.

Scientists from Durham University previously discovered five unidentified “supermassive” black holes, billions of times the size of our sun, sparking fears one could come closer to Earth than previously anticipated.

George Lansbury, from the university’s Centre for Extragalactic Astronomy, said: “Although we have only detected five, when we extrapolate across the whole universe then the predicted numbers are huge.”

Such a black hole wouldn’t need to actually swallow us up. One passing nearby could eject Earth from the solar system and send us hurtling into deep space.

Supermassive black holes

Our galaxy is full of black holes, formed when giant stars collapse in on themselves, and whose gravity is so strong they swallow everything, even the light that may betray their presence.

Scientists from Durham University previously discovered five unidentified “supermassive” black holes, billions of times the size of our sun, sparking fears one could come closer to Earth than previously anticipated.

George Lansbury, from the university’s Centre for Extragalactic Astronomy, said: “Although we have only detected five, when we extrapolate across the whole universe then the predicted numbers are huge.”

Such a black hole wouldn’t need to actually swallow us up. One passing nearby could eject Earth from the solar system and send us hurtling into deep space.

Mile-long asteroids raining down

An asteroid big enough to wipe out civilisation on Earth, experts agree, would need to be at least a mile across – and that kind of impact only happens once every million years or so.

It is believed the dinosaurs were wiped out by a six-mile-wide asteroid which slammed into Earth 66 million years ago.

In a paper by Oxford University’s Future of Humanity Institute, researchers explained the greatest danger will be “clouds of dust projected into the upper atmosphere”, creating an ‘impact winter’ affecting climate and food supplies.

And Bruce Willis can’t come to the rescue either – physicists claim it would be impossible to nuke a Earth-destroying-sized asteroid hurtling towards us.

Supervolcano blowing its top

Volcanoes have form when it comes to making entire species extinct.

The Permo-Triassic Extinction – the biggest extinction event of all time, when 95 per cent of all Earth’s species were wiped out 252 million years ago – coincided with the largest known volcano eruption in history, in today’s Siberia.

Many believe the next Earth-changing eruption is long overdue, and point to the supervolcano in America’s Yellowstone National Park as the most likely to destroy us.

The Yellowstone volcano erupts with a near-clockwork cycle of every 600,000 years – and that last eruption was more than 640,000 years ago.

Scientists have discovered that the ground in Yellowstone is 74cm higher than it was in 1923, indicating a massive swelling underneath the park.

Experts predict that when it blows its top again the consequences for the world will be catastrophic.

Within minutes of the explosion tens of thousands would be dead and the long-term effects would be even more devastating.

The Sun would be blocked by ash, temperatures would plummet by 21 degrees, rain would turn to acid, and most if not all of the world’s humans would be wiped out.

Gamma ray burst

Gamma ray bursts are flashes of gamma ray light, probably caused by the merging of two collapsed stars, and are the most powerful explosions of energy in the universe – as much as 10 quadrillion times as energetic as the Sun.

So far, the bursts – which are detected from Earth about once a day – have happened in distant galaxies millions of light-years away.

If such an event were to happen closer to home, the intense flash of gamma rays illuminating the Earth for 10 seconds would cook the atmosphere and destroy the ozone layer, causing a massive extinction event.

Astronomers point out double stars are almost completely undetectable and we would have no advanced warning until the moment it hits us.

Rise of the machines

The Terminator may be science fiction, but robotic killing machines capable of thinking and acting on their own are not far from becoming a reality.

The United Nations previously called for a ban on killer robots – presumably because experts feared that several countries were developing them.

Inventor Elon Musk, co-founder of Paypal, has warned that artificial intelligence might be the “greatest existential threat” that humans face.

And the late Stephen Hawking said: “The development of full artificial intelligence could spell the end of the human race. Humans, who are limited by slow biological evolution, couldn’t compete, and would be superseded.”

Dying Sun pulls Earth in

Even if we manage to avoid asteroid collisions and robots becoming our overlords, there is no escaping the Sun itself.

Currently, the star is halfway through its life cycle – but when it begins to die in billions of years, it will begin to expand.

Running low on hydrogen, it will begin fusing helium, a process that will push its layers outwards.

As a result, not only will its surface grow closer towards Earth, but its gravitational pull could also pull the blue planet in.

Eventually, the Earth would be vaporised – or thrown wildly out of orbit into the cold depths of space.

Aliens plundering the ocean

There is every chance that, somewhere in billions of galaxies, intelligent beings much more superior to ourselves do exist

So if aliens did finally arrive at planet Earth in large numbers, what can we most likely expect?

Hawking, who helped launch a major effort to search for alien life in the cosmos, thought it more likely that such creatures would come to Earth in search of resources and bent on our destruction.

He said: “If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn’t turn out well for the Native Americans.”

Other cosmologists go further, supposing that extraterrestrial invaders might plunder a vital natural resource, such as the water from our oceans, bring with them pests with a taste for human flesh or upset our planet or solar system causing Earth’s destruction.

‘Rogue planet’ comes crashing in

When solar systems are formed, the huge energy can often kick entire planets out of orbit.

One of the more unlikely doomsday scenarios predicts that such ‘rogue planets’ could either drift into the Milky Way and destabilise the Earth – or just crash into us completely.

If such a planet was big enough, it could cut the Earth adrift from its orbit, turning it into an icy ‘rogue planet’ itself.

Even just a change in gravitational shift could cause extreme weather patterns alternative between freezing winters and unbearably hot summers.

One theory even suggests a rogue planet could make a direct hit with Earth – and it wouldn’t be totally unprecedented.

According to NASA, the Moon was formed when a ‘proto-Earth’ collided with another planet about the size of Mars.

The ‘Big Rip’ ends entire universe

The destruction of life on Earth? That’s small fry in comparison to the ultimate death knell – the end of the entire universe.

The ‘Big Rip’ theory suggests that the universe is expanding due to ‘dark energy’, with galaxies moving further and further away from each other.