It takes millennia for the sunlight to get to the surface from the core and then it can escape the star to reach us.
From our school textbooks, we know that the sunlight takes around 8 minutes and 20 seconds to reach the Earth.
After reading the title of this post, you may ask, then what the hell I am talking about? Let me explain.
The 8-minute plus figure we know is the time taken for the light to travel from the Sun’s surface to the Earth.
That is around 150 million km of distance. Light travels at 300 thousand km each second. We do the division and get that time frame.
But the sunlight we see isn’t emanating from the Sun’s surface originally. It is created at the core of the star. And the light takes thousands of years to reach the surface from the core.
At the core, billions of atoms are participating in nuclear fission and fusion. Those processes create high-energy gamma rays that human eyes can’t detect.
Once produced, the gamma-ray particles, called photons, start to make a commute from the core to the edge of the hot, giant ball.
As the commute starts, the photons get absorbed by charged ions and emitted only to get reabsorbed.
After each such collision with ions, a photon scatters in a random direction and its energy content dissipates. As the energy level drops, human eyes become capable to detect these moderately energized particles.
Now, neither the space length nor the directions are the same between the two collisions. Simple arithmetic crumbles apart. So, scientists need to take firm mathematical assumptions into account.
One such assumption is the random walk process.
If a human being walks 1 meter with each step and takes N number of randomly scattered steps, then the distance walked would be a squared route of N.
That means, walking 10 meters would take 100 random steps, 100 meters would require 10 thousand, and for 1000 meters, a whopping 1 million steps. Tricky, right?
Also, the core is super dense, and the density drops by tens of thousands of times toward the surface of the star.
As a photon navigates out of the core, it encounters large spherical shells of matter that are nested inside bigger ones.
If the random walk process and the nested structure of the Sun’s core are assumed, a photon needs to travel for 10 to 170 thousand years to reach the edge to escape the star.
And then, 8 plus minutes to end up on Earth. Since there is empty space between the star and our planet, photons travel straight and our middle school arithmetic starts to work again.
In the end, if the Sun’s exterior is covered with bigger celestial objects, we shall know in only a few minutes. But if its core is doused, it would take us thousands of years to finally figure out that we are doomed.