Once a photon of light is generated, how long does it take to escape beyond the outer part of the Sun?

Question

Nolan Aldridge · Accepted Answer

It takes thousands of years for a photon to get from the sun's core to escape from the surface.

A photon is created in the sun's core and travels to the surface, colliding with numerous protons and electrons. This is an example of the drunkard's walk problem: the photon effectively has to find a path to the surface by being randomly absorbed and re-emitted by particles along the way. The number of steps, between particles on the way #n# can be calculated by the formula #n=R^2/d^2#. Where #R=6.96*10^8#m is the distance to travel - radius of the Sun and #d# is the free mean path - the distance between particles. The value of #d# is estimated to be about 1 centimetre. Putting #d=0.01# into the formula gives #n=4.8*10^(21)# steps. The time taken for each step is #t=d/c# where #c=2.99*10^8#m/s is the speed of light. This gives #t=3.3*10^(-11)# seconds. This gives a total time #T=nt=1.58*10^(11)# seconds. Given that a year is #3.1*10^7# seconds. This gives #T=5109# years. It takes thousands of years to travel that distance, and this calculation assumes that the free mean step is actually about a centimeter. It could be much smaller, which would lengthen the time.

Jordan Andrews · Answer

undefined After being created in the Sun's core, a photon of light must travel through several layers of the interior for 100,000 to 200,000 years before it can finally be released into the photosphere, the outermost region of the Sun.

Henry Asbill · Answer

undefined It takes about 10,000 to 170,000 years for a photon of light generated in the core of the Sun to travel through its radiative zone to the convective zone and finally escape beyond the outer part of the Sun.