photons and the sun

(quotes from an Open University textbook about the universe and how it works)

"nuclear fusion reaction in the core starts with two protons colliding and fusing to form a nucleus of deuterium. "The chance of any particular proton reacting with another proton is extremely rare - on average an individual proton will have to wait for more than 10 billion years before such a reaction happens."

"Fusion occurs in the central 2% of the sun's volume, 400,000km in diameter containing 60% of its mass. A product of this reaction is a gamma-ray photon."

"Scattering of photons by electrons. When a photon encounters a free electron, its direction and energy will change." " a photon typically travels only about 0.1mm between each scattering event."

"Energy released in the centre has been estimated to take several million years to reach the surface."

"a single X-ray photon produced in the core of the sun may give rise to many tens of thousands of photons of visible radiation by the time the energy has been transported to the outer layers."

"from the time it leaves the photosphere, a photon takes about eight minutes to travel to the earth, bounce off the page in front of you, enter your eye and create an electrical response on your retina."