Link #155: The Sun Will Swallow Earth In 5 Billion Years!

Oct 17, 2016

Red Giant Earth — Image credit: Fsgregs/CC BY-SA 3.0

Link #155: The Sun Will Swallow Earth In 5 Billion Years!

In our last post, we mentioned how humans are unique amongst all animals on Earth. We specifically spoke about the border that we, humans, have around our lips and how no other animal on the planet has it.

Still, no matter how unique humanity is on Earth, we will share the fate of all animals when the Sun decides to swallow Earth five billion years in the future. That’s right. There may be no Earth in five billion years. Even if there’s an Earth, there will be no life on it. How? Read on.

How Will The Sun Swallow Earth?

Life on Earth has always depended on the light and heat from the Sun. Without the sun, the planet would get too cold, vegetation wouldn’t grow, and all life would cease to exist.

Since the Sun is one massive engine that converts hydrogen nuclei to helium nuclei, it will sooner or later run out of hydrogen nuclei and stop generating all the light and heat that we depend upon.

However, long before that can happen, the Sun will swallow up our planet. In about five billion years from now (give or take a few million years), the Sun will start running low on hydrogen nuclei in its core, as there will be more helium nuclei than hydrogen nuclei.

This will increase the inward pressure in the core since there will be no reactions generating energy that will counter the gravitational pull. When the core of the Sun will start to compress, temperature will start to increase.

This increasing temperature will result in the conversion of hydrogen nuclei in the outer layers of the Sun to helium nuclei. So, because of these reactions, the outer shell of the Sun will start expanding.

How much will it expand? It’ll expand to about 250 times its current size. This will bring it very close to Earth but still not cause it to swallow our little planet. The Sun would’ve swallowed Mercury and possibly Venus by this time.

The older theory states that this expansion will cause the Sun to lose its gravitational pull. However, scientists now expect the gravitational pull to be strong enough to pull Earth into an inward spiral. The Earth will orbit closer to the Sun till it vaporises into nothingness!

What Will Happen To The Sun After?

White Dwarf Star — Image credit: NASA, ESA and G. Bacon (STScI)/CC0

When the Sun will expand to 250 times its current size, it would be in its Red Giant phase. When the Sun grows to that huge size, it’ll fail to keep all its material. It’ll lose approximately 30 percent of its total mass.

After this period, the core of the Sun will get ignited in a process known as Helium Flash. During helium flash, the Sun basically consumes its own helium in the core. The process, though, is hidden away from outsiders. Now, the Sun will drop in size to only become 10 percent of its current size.

Following this, there’ll be another phase like the red giant phase. After this, our darling Sun will turn into a White Dwarf that will only shine because of stored thermal energy.