HOW DOES THE SUN CREATE LIGHT?
I have seen several publications describe how our Sun converts about 600 million metric tons (6 x 10¹¹ kg) of hydrogen atoms into helium, per second. This is an impressive figure of solar mass, but can normal people visualize that concept? What does 600 million tons of hydrogen look like? How big is that? Of course, this amount of hydrogen gas (in the form of a super-hot plasma) will be quite compressed in size by the Sun’s gravity, and at the same time it will be super-dense—otherwise, nuclear fusion would not occur at all in any star. (The hydrogen and other atoms must literally be crushed together.)
So, with this in mind, I wish to visualize this concept in an entirely different way. Keep in mind how a star creates light—i.e., electromagnetic energy at visible wavelengths, between 380 nanometers and 750 nanometers. During nuclear fusion of hydrogen into helium, the predominant processes in our Sun are called the P-P (proton-proton) and CNO (carbon-nitrogen-oxygen) cycles. (See my article on this website titled, HOW DOES THE SUN CREATE HEAT?) Well, at certain portions of these P-P and CNO cycles, a gamma ray is emitted, which will slam into another atom (still inside the Sun), which will raise an electron of that slammed-into atom to a higher energy state, which will also release a photon of a given wavelength (depending on which element this atom is, and which quantum energy state is involved for that raised electron orbit).
Eventually—and I mean millions of years later—that photon (or a cousin of that photon after it slams into billions or trillions of other atoms within the Sun, thereby creating photon after photon from those slammed-into atoms) will finally reach the outer surface of the Sun, and begin travelling through space. A very small percentage of the Sun’s space-travelling photons will then impact our Earth, and animals with working eyes will see some of these photons as visible light.
Every ‘piece’ of light that you see comes from the Sun, at least during daylight hours as you walk outside. And think of all the objects that you can see, including the details of those objects. For example, look at a building made of bricks. You can see each individual brick, as well as the mortar between those bricks. You are seeing hundreds and thousands of bricks as you look down the street at other buildings. And think of the fact that each little detail that you see travels to your eyes via photons that were originally emitted by the Sun. Imagine the billions, if not trillions, of photons you are seeing as you look around. And then remember that each of those photons was originally created by the Sun, each one in a nuclear reaction that fuses hydrogen into helium via the P-P and CNO cycles. This is an astonishing large number (billions and billions) of photons.
And keep in mind—these photons that you are seeing do not bounce around forever. In other words, they don’t last very long—they become absorbed by objects—plant life, if nothing else. This is perfectly clear during a solar eclipse, when the dark umbra of the moon’s shadow first passes over you. I have personally taken videos of the two most recent total eclipses that have reached the United States (in 2017 and 2024), and I can assure everyone that the Sun’s light goes away quickly (within one second) once the moon’s shadow covers one’s little portion of the Earth’s surface. It is a quite dramatic effect, which is why people were afraid of solar eclipses in the old days.
Finally, keep in mind that you are only seeing a tiny portion of the Sun’s light that actually touches the Earth when you look around your outside neighborhood. And further, keep in mind that the Sun’s total output of photons goes radially outward, everywhere around its sphere—not just to our Earth. Now, multiply the inverse of all those small percentages of light that you can personally see as compared to the Sun’s total output of photons, and you can perhaps conceptually visualize how much power is really being generated by our nearest star. And thank God that the Sun exists as it is, doing all these wonderful things.
FRED GRIBBELL, January 2026
Afterword:
Yes, the Sun is ultimately responsible for global warming. But without the Sun, our Earth would be colder than the ‘planet’ Pluto—now that’s cold! (It’s not absolute zero, but it’s close.)