Even though it’s about 149 million kilometers away from Earth, the Sun has an immense impact on Earth, not just through light and heat, which is are the key factors that make life possible on our planet. Located in the heart of our Solar System, as the largest object among all, containing 99.8 percent of the mass of the entire system, the Sun’s diameter is 109 times bigger than that of Earth, and its volume could hold about one million Earths. The temperature on the surface of the star is about 5,500 degrees Celsius, but that’s just the part of the Sun we are able to see. If we were to look beyond the surface, down to its core, we’d find that the temperatures there can reach up to 15 million degrees Celsius, as a result of nuclear reactions.
It is believed that the Sun was born about 4.6 billions of year out of a giant rotating cloud of gas and dust, known as the solar nebula. When the nebula became large enough, it collapsed onto itself because of its gravity, and started spinning faster until it became a flat disk, with most of the material pulled toward the center, creating the Sun. The Sun will remain unchanged for the next 5 billion years, since it has that much nuclear fuel left. After that, it will morph into a red giant. Over time, it will shed its outer layer, while the remaining core will collapse onto itself, forming a white dwarf. It will begin to fade slowly, until it enters its final phase as cooler, more dim star, known as the black dwarf, which exists only theoretically, since the universe isn’t old enough to have black dwarfs.
The sun and its atmosphere can divided into several layers. The inside, which is made up of the core, radiative zone and the convective zone. The atmosphere can be divided into four layers: the photosphere, the chromosphere, a transition region and the corona. Although it makes up for only 2 percent of the Sun’s mass, the core holds almost half of its mass, seeing as it is 15 times denser than lead. It extends from the center to about one quarter of its diameter, after which comes the radiative zone, spanning from the core to about 70 percent of the diameter, and making up for 32 percent of the Sun’s volume and 48 percent of the mass. A single photon, emitted by the core, can take millions of years to pass through the radiative zone. The convection zone reaches up to the surface, making up for a little more than 2 percent of the Sun’s mass, but it also makes up for 66 percent of its volume.
The chemical composition of the Sun is similar to most stars, consisting mostly of hydrogen and helium. The rest is divided between seven other elements: oxygen, carbon, neon, nitrogen, magnesium, iron and silicon, but that’s almost insignificant, since for every million atoms of hydrogen, there are 98,000 atoms of helium, 850 of oxygen, 360 of carbon, 120 of neon, 11 of nitrogen, 40 magnesium, 35 of iron and 35 of silicon.