The artist’s concept of a giant red star burning a planet in orbit around it. Image by ESO / L. Calçada.
The earth exists because of our sun, which formed in orbit around it from a huge cloud of gas and dust in space, 4.5 billion years ago. Likewise, the sun will destroy the Earth for life, about 5 billion years from now. As the sun evolves, it will expand to become a giant red star and fry our planet in a ember. Moreover, the death of the Earth will take place against a background of galactic change. Our Dairy Galaxy and the Andromeda Galaxy will be in the middle of a colossal collision that will forever change our galactic home into space.
Our sun is a G-type star currently about halfway through its life cycle. This type of star is very stable for most of its life, quietly fusing hydrogen into helium inside it for billions of years. One day, the hydrogen inside the sun will be depleted. At that time, the pressure of the inner gravity will gain over the outer pressure of the internal fusion of the sun, until the sun heats up enough to begin to fuse helium. At that moment, the sun will balloon outwards to become a giant red star.
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As the sun warms and expands, its outer layers will cover the innermost planets, Mercury and Venus. The outer edge of the sun will rise to roughly reach Earth’s orbit. The water and atmosphere of our planet will boil, leaving behind nothing but a charred stone, lifeless. Mars will take some time to warm up, but eventually Mars will be out of the habitable zone for humans as well. At that time, the moons of the outer planets – such as Jupiter and Saturn – will be the only places left in our solar system for human colonies.
But even these locations will be only temporary fixes in search of a new home.
As our sun expands into the huge red phase, the habitable area around it will be pushed outward into the solar system. Image by NASA / Wendy Kenigsburg.
The giant red phase of the sun could continue for about a billion years, but eventually helium will be depleted. Then the sun will blow from a sachet of gas. Astronomers looking through telescopes at other star systems will see our sun as what we call a planetary nebula, a large shell of gas that surrounds a dying star. Eventually, the shell will dissipate into space, and what is left of our sun will become a white dwarf star.
Earth astronomers can look out into space to glimpse the future of the Earth. For example, 400 light-years away, a star known to astronomers as SDSS J1228 + 1040 is a white dwarf with the funerary shroud of its gas nebula, and inside it astronomers have found the signature of a planetesimal orbiting the sun. his home long after his death calamity.
And what about the Milky Way galaxy itself, the great star island that contains our Earth and our sun? Until our sun enters the giant red phase – long before it settles like a white dwarf – the Milky Way itself will undergo a long process of inevitable collision with the giant spiral galaxy next door, the Andromeda galaxy. The last humans on Earth – if humans are left over a few billion years from now – will see the Andromeda galaxy grow even brighter in the night sky. Currently, it is barely visible to the unaided eye from a place with a dark sky. But, over a few billion years from now, the Andromeda galaxy will be an amazing, unmistakable whirlwind of stars easily visible in the night sky of any inhabitant of Earth.
As Andromeda and the Milky Way approach each other, the large mass of the Andromeda galaxy will begin to affect the stars in the Milky Way. Our galaxy is wide and flat, like a pancake. On Earth today, we see the stars on a dark August evening, like a big foggy band in the sky. But as Andromeda’s gravity distorts their paths, the stars of the Milky Way will be scattered across our skies.
It may seem incredible, but the stars in the galaxies are so far apart that even when the two huge spirals collide, there will be few fireworks from collisions between the stars. However, the gas clouds in the two galaxies are likely to collide, forming vast conglomerations of new stars.
This series of illustrations shows the predicted fusion between our Milky Way galaxy and the neighboring galaxy Andromeda. Image via NASA.
Eventually, the Milky Way and the Andromeda galaxies will settle to form a new massive blob-shaped galaxy. At this point, the Earth, our sun, and the rest of our solar system could be in a completely new location from the galactic center. Today, the Earth is about 25,000 light-years from the center of the Milky Way. After Andromeda and the Milky Way merged, astronomers believe that our home in space will have been ripped to a new galactic orbit about 100,000 light-years from the center of the new large combined Andromeda-Milky Way galaxy. As theorist TJ Cox of the Harvard-Smithsonian Center for Astrophysics said:
You could say we’re being sent to a retirement home in the country.
And what will be the fate of humanity? It is impossible to say. If it survives, the future of humanity will depend on our ability to travel far from our dying sun and set up camp elsewhere.
Fortunately, we have several billion years to learn how to accomplish this monumental task.
Conclusion: What will be the fate of the Earth? The earth will become a dry, burnt rock as our sun becomes a giant red star. Moreover, as the Milky Way and the Andromeda galaxies collide, the sun and Earth (and the rest of our solar system) are expected to be thrown outward, away from the galactic center, at the edge of a new colliding galaxy. .
