- In 5 billion years, the Sun will expand to become a red giant star 100 times its current size.
- The inner planets will be destroyed, but the Earth may be spared from consumption.
From an AI apocalypse to full-scale nuclear war, the list of things that could cause the end of the world seems almost endless.
But if those terrible fates befall us, there is only one doomsday event on Earth that is inevitable.
A terrifying diagram reveals how the sun will grow into a massive ‘red giant’, becoming so large that it will spell the end of the solar system as we know it.
This may seem completely shocking, but there’s no need to worry just yet.
Dr Edward Bloomer, senior astronomer at the Royal Observatory Greenwich, said: “It’s probably somewhere around 5 billion years before the sun reaches the red giant stage.” So there’s still time! ”
Our Sun, like all stars, is essentially a giant nuclear reactor that crushes helium atoms under gravity.
This massive gravitational force keeps eight planets and countless other celestial bodies in our solar system in orbit.
Meanwhile, the energy generated by nuclear fusion is radiated into space as heat, forming a habitable zone that extends from just outside Venus to the orbit of Mars.
But Dr Bloomer told MailOnline that eventually everything would change.
About 5 billion to 5.5 billion years from now, the Sun will begin to transform into a red giant.
“This essentially happens when there is no more hydrogen to fuse in the Sun’s core,” Dr. Bloomer explains.
When our sun eventually runs out of hydrogen, its core will begin to collapse under its own gravity.
As the outer layers collapse inward, the pressure and heat become so intense that these layers begin to fuse helium atoms into carbon.
The resulting burst of energy expands the Sun to hundreds of times its original size and cools it from white to red-hot.
Bloomer explains that while this process is “not like flipping a switch,” it will inevitably lead to the destruction of the solar system.
The diameter of the Sun is currently approximately 865,000 miles (1.4 million kilometers).
However, when it becomes a red giant, it can expand more than 200 times this size, reaching up to 186 million miles (300 million kilometers) in diameter.
When this happens, the innermost planets, Mercury and Venus, are drawn into the Sun and destroyed.
However, Bloomer said, “Earth is in an interesting position because we don’t know exactly how big the red giant is.”
At a distance of 93 million miles (148.22 million km) from the Sun, it may seem like the Earth is scorched.
But 186 million miles is the absolute upper limit for the Sun’s growth, and it may never grow this much.
Dr. Bloomer said, “At the upper limit of possible size, the Earth may be completely engulfed by the sun, and that’s the end.” At the lower limit, it may not be consumed.
But even if the sun didn’t swallow the entire Earth, it’s still not good news.
Dr Bloomer said: “Earth’s surface temperatures will mean the atmosphere will be blown away and the oceans will boil.” ‘
He added: “At best, the remaining ‘Earth’ will be a lifeless ball of rock blasted with radioactivity.”
Mars, Jupiter, and Saturn will be blown up by the intense heat of the growing red giant, so no exoplanet will be able to escape unscathed.
If the Sun becomes large enough, it could burn out in a process called photoevaporation, as stellar ejections strip away the surrounding gas.
However, Dr. Bloomer explains that some models predict that Saturn could suddenly find itself in the middle of the Sun’s new habitable region.
“Some models suggest that regions about the distance of Saturn from the sun may be reasonably warm,” he said. We can’t live on Saturn, but perhaps on its moon Titan?
“Due to the extremely low temperatures, there is now a thick, unbreathable atmosphere and lakes of liquid ethane and methane, but understanding what happens there when it heats up is an ongoing process. It is a field of research.”
Finally, about 7 billion years from now, the Sun will completely run out of energy and begin shedding its outer layers into space, leaving planetary nebulae behind.
These vast ring-like structures form when a dying star ejects most of its remaining material before becoming a hot white dwarf.
Last year, scientists used the James Webb Space Telescope to take images of Messier 57, or the Ring Nebula. This gives us a hint of what our sun will someday look like.
And in these final stages, the Sun will remove the outermost planets from its orbit, completing the transformation of the Solar System.
When the Sun loses 50 percent of its mass in this process, the force becomes so strong that Uranus and Neptune are simply wiped out of the solar system.
Finally, when it comes to the asteroid belt and Oort Cloud, which also orbit the Sun, how severely they are affected depends on distance.
As the Sun expands to its final gigantic size, objects in the asteroid belt may become so heated that frozen gas and water sublimate, leaving only their metallic cores.
But little has changed in the Oort Cloud, a vast expanse of rocky material located between 0.079 and 1.58 light-years from the Sun.
“In some ways, they may not actually be aware of it as much because they’re simply too far away,” says Dr. Bloomer.
“But things like changes in the solar system’s angular momentum caused by the expansion of the sun can perturb places like the Oort cloud a little, changing the orbits of objects in that vast region.
“But in general, the changes will not be as big as the effects on the inner solar system.”