Observing the sun.

Hi PJ,
The question is:
Once we "shut-down the thermonuclear fussion reactions in the solar core", when shall we observe lights-out from Earth?

The answer is:
100.000 years + 8.21 minutes thereafter.
Or maybe, according to others:
1.000.000 years + 8.21 minutes thereafter.

The reason is that the photons from the core do take that long time to reach the photosphere and escape from the Sun.
This long time is due to the phenomenon called "random photon walk".

So, if someone shuts the Sun down, we will have at least 100.000 years of sunlight (and solar heating).
PS: OK, plus 8.21 min BONUS time!

I knew that,lol.

Sure, lol.

The edges of the solar disc -the limb- appear darker to the human eye than the center of the sun (the solar sphere actually), which appears more "illuminated". Can you guess why is that so?

That's easy:


The density of the star diminishes as the distance from the center increases and also the temperature of the star diminishes as the distance from the center increases.

Its kind of like a cup of coffee or any hot liguid. The surface of the liquid is cooler then the rest of it.

Yeah PJ, Wikipedia is always right, of course!

Indeed it is. If you cant trust Wiki.........what can you trust?

"random photon walk"

Surely you mean "random motion walk"