Nuclear Reactions in the Sun

core (15 million oK!), photosphere (visible surface, 5700 oK, photons no longer collide, can escape), chromosphere (10,000 oK), corona (2 million oK, low density, but high temperature due to magnetic fields and violent convective motions of lower layers, source of X-rays)

Why are chromosphere and corona hotter than photosphere even though they are further from core?

How do we know about Sun's interior?

What is the Sun's energy source?

Einstein's beautiful logic...

... if speed of light constant, leads to funny effects!



How the Sun generates energy... and converts itself from hydrogen to helium

Proton-Proton (pp) chain (high energy protons released, which then participate in new reactions) is one way:

And there is the CNO cycle...

At the end, products are 0.7 percent less massive than the initial matter.

Every second, Sun converts 4 million tons of hydrogen to energy and radiates it into space!

It would take another 4 billion years to consume all the Sun's hydrogen.

Fusion only happens in the core (107 K).

Detection and Mass of Neutrinos

Click here for some FAQ's about neutrinos.