How the Sun Works

It is the source of all life on the planet, yet for the longest time mankind thought that the Sun revolved around us. Once we discovered that was not the case we began to learn much more about how our very own star works and provides much needed light and heat to our world.

A Look at How the Sun Works

The best way to see how the Sun works is to understand its composition. As a terrestrial planet like Earth has a Core, a Mantle and a Crust, so the sun has three surface areas; Core, Radiative zone, and Convective zone. It also has three parts to its atmosphere; the Photosphere, the Chromosphere and the Corona.

The Sun's Core

Here is where the majority of the sun's energy production takes place, in the area that starts at the centre of the sun out to 25 percent of its radius. The gravity of the sun has two effects; first it holds the whole ball of gas together, and second, the immense pressure smashes atoms of hydrogen together, creating nuclear fusion. Some 85 percent of the sun's energy is created by this nuclear fusion at the core, which releases that energy—in both a direct and a round about fashion—which eventually finds its way to Earth as visible sunlight.

The Sun's Radiate Zone

From the core out to about 55 percent of the sun's radius is the Radiate Zone. This area is where the energy created at the core is transferred outward (radiated) by photons. Here is the round about method of energy release; each photon only travels 1 micron, which is one millionth of a metre, before it is absorbed by a gas molecule. This photon is then released in a random direction and then reabsorbed. By the time that photon makes its way out of the Sun as much as 50 million years may have passed.

The Sun's Convective Zone

The rest of the sun's surface radius is taken up by the Convective Zone, which gets its name by the convection currents that carry energy the rest of the way to the surface. Currents of hot gas rise while currents of cooler gas fall, creating a cycle that carry photons much faster than from the Radiative Zone—about 100,000 years.

The Photosphere Of The Sun

The portion of the sun visible from Earth is the Photosphere, the lower part of the Sun's atmosphere that is around 400 kilometres thick. The average temperature of the Photosphere is around 5,800 Kelvin and appears to bubble and roil. Each "bubble" is the top of an upward moving convection current and can stretch 1,000 kilometres wide.

The Sun Chromosphere

Above the Photosphere in the sun's atmosphere and reaching up 2,000 kilometres is the Chromosphere, where the temperature soars to as much as 10,000 Kelvin. Scientists are stumped as to why the temperature is higher here than closer to the sun's surface, but some surmise that churning gases between the two spheres produce shock waves that add heat energy.

The Sun's Corona

The Corona is the uppermost area of the sun's atmosphere and reaches an amazing several million kilometres out from the Photosphere, and here the temperature goes off the charts to an average of 2 million Kelvin. Some theories as to the temperature jump have to do with he sun's magnetic field, but no one is certain.

Final Thoughts

The Sun is a self generating nuclear explosion, a nuclear fusion, constantly providing energy to our solar system, which it has done for around 4 billion years. Sol, as it is called in Latin, is about middle age, but with another 4 to 6 billion years to enjoy its life giving energy, there is little to worry and plenty of time to learn more about how the Sun works.