What’s that up in the sky? It’s a bird, it’s a plane, no -- it’s
the Sun. Oh… The Sun, as we know it, is a bright, friendly
ball that makes life on Earth possible. Earth isn’t the only planet in the Solar
system, and yet, it’s the only one with complex forms of life. So it’s not just that the friendly Sun makes
our planet an oasis in a vast space desert. The Sun could also finally be the most harmful
thing our planet will face. But, more on that in a bit. Can you believe that the Sun doesn’t care
about us? Or life. Or planets. It’s highly radioactive, and it’s already
destroyed the atmosphere and oceans on Mars. Is it going to destroy Earth too? Or do we have a chance to survive? Well, unlike other planets, the Earth is protected
from radiation. Deep inside its mantle, there’s a mixture
of boiling metals that create a huge magnetic field around the Earth. It’s good for us because that field doesn’t
allow radiation to reach the surface. There’s also an ozone layer, which works
the same way. Earth is located in the so-called Goldilocks
zone, or circumstellar habitable zone. What that technical gobbledygook means is,
it’s not too far and not too close to the Sun, and water can exist in its 3 states here
– liquid, gas and solid. These are basically ideal conditions for all
living beings. Hollywood has shown us dozens of dangers that
could destroy life on the blue planet – from a huge asteroid, to the invasion of aliens. But there’s a real danger that could eventually
burn all signs of life away (unless asteroids and aliens don’t do it first), and that’s
the Sun. Like any star, it goes through different phases
of evolution – from a cloud of star dust to a dense stellar remnant – a white dwarf. Now, the Sun is somewhere in the middle of
its life. Hydrogen inside its core burns and turns into
helium; the same one we fill balloons with, right. But if you inhale the sun, instead of sounding
goofy, you’d just burn up. Bad idea. Scientists say that it’ll take about 7 billion
years for all the hydrogen to burn away and be replaced by helium. As a result, the Sun will be getting hotter
and brighter – by about 10% every billion years. And this is where the problems for the planets
start, as the average temperature on the surface of the Earth will be 120 °F higher. This will lead to a greenhouse effect like
what we see on Venus now. In the long run, the water will be blown away
from the atmosphere by a stronger solar emission. In 3.5 billion years the Sun will be 40 % brighter
than it is now. Imagine a frying pan with water in it left
on a sunlit kitchen table. The water would evaporate almost immediately. And this is what’ll happen to the oceans
at that time. They’ll become so hot that they’ll evaporate
without boiling. Needless to say, but I’ll say it anyways,
It’ll be a very hard time for plants and animals. Only some will survive, but not for long. When steam gets into the atmosphere, the Solar
ultraviolet light will decompose water molecules and hydrogen, which are necessary to build
any living cell, and spread them into space. The Sun will keep growing and eventually turn
into a red giant, which will absorb Mercury, Venus and probably Earth. But even if our home survives, it’ll be
a roasted piece of rock rather than the beautiful blue planet we’ve known our whole life. You’re upset that our best friend is going
to betray us? Cheer up! 7 billion years is plenty long enough
to prepare for survival. And here are the solutions that scientists
can offer. One of the most obvious decisions would be
to leave the sinking ship in a lifeboat. Or rather, fly away in a spaceship. In 1930, British science fiction author, Olaf
Stapledon, described a future when Earth becomes uninhabitable and the next generations had
to move to Venus and Neptune. Stephen Hawking, like some other outstanding
scientists, thought it was necessary to create a human colony on other planets and the Moon
so that human beings could survive any catastrophe capable of destroying life on Earth. But let’s come back to escaping the planet. To evacuate 7 billion people, we would need
about a billion space shuttles. Even if we launched 1000 shuttles daily, which
is – well – impossible, it would take 2700 years to move all the population from
the planet. And yes, since Venus would be destroyed too,
we’d have to get much father from the Sun; and the flight would take years. And if you think weightlessness is fun, you’d
be disappointed. Without gravity, our bodies age quickly and
develop all sorts of illnesses. Years without gravity and protection from
solar radiation will do no good to anyone. And then, it’s not like there’s a comfortable
5-star hotel on a different planet, waiting for us to move in. People on Earth need oxygen to breathe, gravity
to walk, water to drink, food to eat. The conditions we need to live are too complicated
to reproduce anywhere outside the Earth. This is exactly what drove scientists to a
surprising idea. Why not take Earth, with all its resources
and inhabitants, and move it to a safe distance from the Sun? Scientists say that when the Sun turns into
a Red giant, the Goldilocks zone will be 1.5 times farther from where it currently is,
which is where Mars’s orbit is now. Sounds crazy, and yet scientists have a way
to solve this too. Launching a rocket into space pushes Earth
in the opposite direction, just like a backfire. The problem here is that the Earth is too
big, and it would take a billion 10-ton rockets launched in the same direction to change the
Earth’s speed by 20 nanometers per second. That’s nothing compared with its actual
speed of 19 miles per second. Another way is roughly what we saw in “Armageddon”:
a nuclear explosion close to or on the surface of a space body can change its trajectory. It can work well with an asteroid; the film
wasn’t that far off after all. But the problem with Earth again is that it’s
too big. And another thing: any explosion means destruction,
and that’s what we’re trying to avoid in the first place. Since the Earth’s size and mass are not
to be sniffed at, maybe we need some method where they aren’t important. Light has energy but doesn’t have mass. A focused ray of light, such as a laser, can
take energy from the Sun, and in that case the Earth’s mass is irrelevant. And yet, even if we use a huge and powerful
laser like Breakthrough Starshot, whose goal is to deliver a spaceship outside the Solar
system to explore the neighboring stars, it would still take 3 billion years to change
the orbit of the planet. We could also reflect the Solar energy directly
with a kind of Solar canvass built close to Earth. Sounds good, but it would have to be really
big – 19 times bigger than the Earth’s diameter. Well, maybe one day we’ll have the right
kind of technology. After all, a billion years is 5000 times longer
than Homo sapiens have been living on the planet. Look how far we’ve come from living in caves
and chasing mammoths! We might think up something useful by that
time. There’s still another way to save our home
from the growing Sun. It’s a kind of interplanetary pool. The technique known as a gravity slingshot
is used for 2 rotating bodies and uses their gravity to change the speed. It’s been widely used for launching interplanetary
explorers. Let’s say, spaceship Rosetta, which visited
comet 67P in 2014-2016, came close to the Earth twice during its 10 years’ journey
to get a speed-up from it. Without this boost, its mission would’ve
been impossible. I wonder why they didn’t just send Tom Cruise
– he would have dealt with this for sure. Ok, kidding aside. The planet got an impulse from the explorer
too. It had no effect on Earth just because it’s
so big, but what if we could use something bigger? Say, asteroids. They can influence the Earth’s trajectory. Maybe a single time wouldn’t have much effect,
but this action can be repeated a lot of times to reach the goal. Some places in the Solar system are full of
small asteroids and comets – even modern technologies are enough to move them. Donald Korycansky and Gregory Laughlin from
the University of California and Fred C. Adams from Michigan have developed that idea. They say that if we take an asteroid with
a 60-mile diameter and put engines in it, it’ll pass the Earth's orbit every 6000
years, each time giving it part of the energy. As a result, the planet will be thrown out
18 miles, just like a swimmer pushed out by a wave from a passing motor boat. After 6 billion years and a million meetings
with the asteroid, it’ll reach the orbit of Mars. Look easy? Well, it's still a theory. It's one thing to move a small spaceship,
and quite another to move a whole asteroid that could destroy life on the planet if the
scientists miscalculate. Oops. My bad. Let's hope they think up something safer by
the time we need to do something ASAP. Do you think human beings will leave Earth
for another planet or move it to a different orbit? Let me know down in the comments! If you learned something new today, then give
this video a like and share it with a friend. But – hey! – don’t go moving your orbit
just yet! We have over 2,000 cool videos for you to
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video, click on it, and enjoy! Stay on the Bright Side of life!
