Catching 170,000 year old Light at Home
Do you know what you can do from your living room? You can catch 170 thousand year old light.
There was a solar eclipse on 21 June 2020, so I decided to make an apparatus to watch it without burning my eyes.
The apparatus allowed me to watch the light coming from the sun safely. It is really easy to make, you just need a shoe-box, foil, tape, scissors and a pin. What I actually made is a pin-hole camera. There are many explanation online to make one.
Now you might ask, what is the 170,000 year old light thing all about. Actually the light or photons (particles of light) from the sun are very very very old. So when I saw the image of the sun from my pin-hole camera I was watching light from the Palaeolithic Era.
Age of Sunlight
Light takes around 8 minutes and 20 second to reach earth from sun’s surface. But sunlight does not form on the surface. It forms almost 670,000 km deeper than that. Light (more accurately photons) are actually a byproduct of the nuclear fusion of hydrogen. So it makes sense that light is made where the fusion occurs which is mostly in the core of our neighbourhood fireball.
The path that light or photons take from the core to the surface is not straightforward. It bounces around protons and other nuclear particles like a pinball. So to calculate the time it takes for it to reach the surface is not really easy.
Random Walk Problem
The Random Walk problem is a topic in mathematics that is regarding such kind of ricocheting pinball motion. When we use our model of the distributions of particles in the sun and plug it into the random walk problem with the speed of light, we get 170,000 years for the path that light takes from the core to the surface of the sun.
To put that into perspective, at that time woolly mammoths and saber-toothed tiger roamed the earth. At the same time humans first started to wear clothes.
This really helps us to realise and admire how small of a fraction we are in this ginormous, really really old and fascinating universe.
Stay Safe. Keep Learning.