Buzz
It's widely known that eventually, the Sun will reach the end of its life. With an expected lifespan of approximately ten billion years, we are already halfway through its journey. This raises an intriguing question: What will happen once the Sun exhausts its fuel?
Gradually, the Sun converts its hydrogen into helium through a process called the proton-proton chain. The Sun’s demise begins when it runs out of hydrogen. Fortunately, we still have plenty of time before that occurs.
10. The Greenhouse Effect Will Become Intensified
Once the Sun depletes its hydrogen, it will start to shine much brighter. As its brightness increases, more of its energy will reach Earth. Our atmosphere, with gases like carbon dioxide, methane, and nitrous oxide, acts as a blanket, trapping the heat from the Sun and making life possible. With the Sun working harder, these gases will trap even more energy, raising Earth's temperature to extreme levels, causing water to evaporate globally and form a thick cloud layer in the atmosphere.
This thick cloud layer will shield Earth's surface from the Sun's harmful radiation for a period of time. However, as time passes, the heat will become unbearable, and the oceans will begin to boil. By then, life on Earth will be impossible. If we haven't perished by then, the lack of water and extreme heat will undoubtedly cause our demise.
9. The Sun Will Grow Larger
Not only will the Sun shine much more brightly, but its size will increase dramatically. Once it exhausts its fuel, it will enter the next stage of its life cycle: the red giant phase. Despite its increase in size, the temperature of the red giant phase will be much lower, around 2,000 to 3,000 degrees Celsius. While still hot, this is significantly cooler compared to the Sun’s typical surface temperature of about 5,000 to 9,000 degrees Celsius.
While this is how the Sun will eventually meet its end, it’s not the same for all stars. Smaller stars, known as red dwarfs, are so feeble that they simply burn out once they run out of fuel (though they last much longer than other stars). On the flip side, massive blue and white giants are so large that they continue fusing heavier elements until they form an iron core, which leads them to explode as a supernova.
8. ...And Then It Will Contract
As time progresses, the Sun will keep evolving. Once it completes the helium fusion, it won’t be able to fuse carbon, leading it to shrink into a white dwarf. This phase will be much smaller than the original size of the Sun.
White dwarfs have much less energy compared to their earlier stages, but they possess remarkable longevity. These remnants continue to emit light for billions of years, eventually turning into cold black dwarfs. The exact duration of this process is uncertain, as astronomers believe the universe is still too young for any black dwarfs to have emerged!
7. Earth’s Orbit Will Shift
By the time the Sun reaches the end of its life, Earth will have long lost all its life. But the planet won’t stop moving. As the Sun enters its red giant phase, it will expand to at least three-quarters of the current distance between Earth and the Sun.
You might assume that our planet would burn to a crisp, but surprisingly, the opposite occurs. As the Sun expands closer to Earth, the gravitational pull on Earth and nearby planets actually weakens. This reduction in gravitational force causes the planets to drift away from the Sun, settling into safer orbits away from the intensified star (except Mercury and Venus, which will be swallowed). Naturally, all life would have already perished, rendering this escape futile for Earth.
6. Life May Appear Elsewhere
Although Earth would no longer support life by the time the Sun becomes a red giant, life could potentially emerge in other locations. Both Jupiter and Saturn are massive planets with numerous moons that could offer habitable conditions.
Europa and Ganymede are two moons that currently harbor ice. While it might not seem like an ideal environment (except for Europa's subsurface ocean), as the Sun expands, its increased size could bring it closer to these moons, possibly warming the ice and creating conditions that could support life resembling the familiar forms we know.
5. Our Galaxy and the Andromeda Galaxy Will Merge
Although this cosmic event isn’t directly triggered by the Sun’s death, it will coincide with it. The first encounter of our two galaxies will occur as the Sun approaches the end of its life. The Milky Way and Andromeda galaxies are speeding toward each other—at a rate of 402,000 kilometers per hour—meaning a collision is inevitable. It might sound alarming to imagine two enormous galaxies crashing together, but in truth, our solar system, including the Sun, will likely remain unaffected.
Of course, we’ll be fine until the Sun finishes its life cycle. As the galaxies merge, the Sun will continue its transformation in this new, combined galaxy. If life somehow survives to this point, the residents will be treated to a spectacular light display as the gases and stars from both galaxies collide.
4. The Outer Solar System Will Finally Feel the Heat
As mentioned earlier, the Sun will expand significantly and grow much brighter as it nears the end of its life. This will transform the nearby planets into scorching wastelands, but what about the distant planets and dwarf planets that are freezing cold? Take Pluto as an example: Right now, its temperature ranges from –233 to –223 degrees Celsius (–387 to –369 °F), which is extremely cold.
However, as the Sun gets closer, it will start warming up Pluto and other outer bodies. While life is unlikely to form due to the lack of necessary conditions, these planets will remain as warm remnants of what the solar system once was.
This will change when the Sun shrinks into a white dwarf, but at least the outer solar system will experience a brief period of warmth from the Sun before it fades away forever.
3. Humans Could Find Another Way to Survive
It’s difficult to predict precisely what kind of technology we’ll have in the future, but imagining the possibilities is exciting. We’re already on the verge of witnessing self-driving cars and other futuristic innovations. Who knows, perhaps before our time is up, we might discover a way to travel to distant planets. There are locations that could potentially support life, so if it ever came down to it, we could explore them. It’s even possible that humanity will have already expanded beyond our solar system into many other star systems by the time the Sun reaches its end.
NASA is already working on a mission to Mars, with many other companies vying to be the first to establish a colony on the red planet. If successful, such a mission could be a game-changer for the future of the human race. The plan is to send humans to Mars by the 2030s, which isn’t too far away. Of course, Mars would be a small challenge compared to traveling to an entirely new galaxy. But as Neil Armstrong famously said, “That’s one small step for man, one giant leap for mankind.”
We must hope that we can avoid any other catastrophic events before we have the opportunity to explore the universe. Much of what lies out there remains a mystery—our telescopes can only capture so much. We don’t fully understand the vastness of the universe, nor do we fully comprehend our own potential. Even though the Sun’s demise might seem like the end of life as we know it, we could be mistaken. For all we know, our intellect might carry us further into the cosmos than we can possibly imagine.
2. Asteroids Won’t Go Far
We’re familiar with the idea of asteroids roaming through our solar system, but surprisingly, they may encounter difficulties when the Sun enters its white dwarf phase. By then, Jupiter and the other outer planets will have adjusted their orbits to match the Sun’s radical transformation. With Jupiter’s massive size and immense gravitational pull, it will continue to exert a heavy influence, disrupting asteroid orbits and potentially ejecting them from our solar system. They might even be drawn toward the white dwarf or torn apart into dust.
Scientists can make predictions about the Sun’s fate by studying current white dwarf stars. Although much research remains to be done on what will happen when our Sun enters this phase, astronomers have observed that areas around white dwarfs are filled with dust. This indicates that rocky bodies once orbited the stars and were eventually shattered into particles, forming the dust we see today.
1. Human Life Will Be Impossible on Earth
Life may arise elsewhere in the universe, but it will certainly not exist on Earth. Unfortunately, everything we have worked for will be destroyed when the Sun dies. Earth’s surface will become unbearably hot, making it impossible for life to survive. Even if we somehow develop advanced technology to combat the heat, it’s unlikely we could grow food or find drinkable water. All the essentials for survival will vanish.
It’s strange to think that eventually, everything we know will be irrelevant. The Internet will be long gone, as will every trace of our Earth. That’s why it’s hopeful to think that life could start anew somewhere else. However, it’s highly unlikely that this new life will resemble humanity. Even if it shares similar traits, it will take billions of years for new life-forms to evolve to the level we are today.
