The Sun is the star at the centre of our solar system and is responsible for the Earth’s climate and weather. The Sun is an almost perfect sphere with a difference of just 6 miles in diameter between the poles and the equator. The average radius of the Sun is 432 168 miles (109.2 x that of the Earth) of which 20–25% is the core.
1. Every second of every day, the sun converts 700 million tons of hydrogen into 695 million tons of helium. The other 5 million tons becomes energy, every second.
2. The current age of sun is 4.6 billion years and it will exist for another 5 billion years.
3. The diameter of this star is 1,392,684 kilometers while its circumference calculated at its equator is 4,370,005.6 kilometers.
4. The surface temperature of the star is 5,500 degrees Celsius while the temperature at its core can reach up to 27 million degrees on Celsius scale.
5. The sun’s total mass is 1,989,100,000,000,000,000,000 billion kilograms, which is 333,060 times the total mass of Earth.
6. The sun is so large that 960,000 spherical Earths could easily fit inside it. If no space was to be wasted and the Earths are squeezed inside the sun, the total number of Earths that would fit inside it would be a staggering 1,300,000!
7. Sun is made of hydrogen. This hydrogen is converted into helium through a process called Nuclear Fusion (opposite to Nuclear Fission). It is this atomic reaction that causes the enormous heat and light emitted by the sun. Once the all hydrogen is converted into helium, the sun will die. This will happen 5 billion years from now.
8. Hot objects are known to expand. So, sun is continuously expanding. This expansion would have caused sun to explode like a massive nuclear bomb but its internal gravitational pull prevents it from exploding.
9. Because the sun is continuously expanding, it will eventually suck in Mercury, Venus and Earth by the time all its hydrogen is converted into helium. When all hydrogen gets converted into helium, the sun will become a red giant.
10. Once the sun reaches or attains its red giant state, it will then start to gradually shrink under its own internal and massive gravitational pull. It will eventually collapse into the size of our Earth while retaining its original mass. It will then be called a white dwarf.
11. Currently sun is made of both hydrogen and helium. ¾th of the total mass of sun is made of hydrogen and helium gives the remaining mass. However, it also contains other elements. For every 1 million hydrogen atoms, sun has 35 silicon atoms, 35 iron atoms, 40 magnesium atoms, 110 nitrogen atoms, 120 neon atoms, 360 carbon atoms, 850 oxygen atoms and 98,000 helium atoms.
12. Light from sun takes 8 minutes and 20 seconds to reach our planet Earth. But interestingly, the same light actually takes 10,000 to 170,000 years to travel to sun’s surface from the sun’s core!
13. Sun’s core is about 2% of its total mass and extends only up to a quarter from the center to the surface. This core is denser than lead. Following the core is the radiative zone and then comes the connective zone.
14. Sun has an atmosphere of its own (it however cannot support life). Beyond the connective zone is the photosphere, followed by chromosphere and then the transition region followed by corona. Beyond the corona we find solar wind, which is actually a gaseous outflow.
15. The light we see from the sun is actually emitted out from the photosphere which is the lowermost layer of sun’s atmosphere. Photosphere is nearly 500 kilometers thick. This layer has a temperature of 6,125 degrees Celsius.
16. The next layer is the chromosphere which is around 1000 kilometers thick. This layer is made of structures called spicules. These are spiky structures. This layer is hotter and has a temperature of 19,725 degrees Celsius.
17. Following the chromosphere is the transition region that extends several thousand kilometers above the chromosphere. This region is responsible for giving out the UV rays.
18. Above the transition region is the corona. This is made of streams and loops of ionized gases. The corona generally has an average temperature of 500,000 degrees Celsius to 6 million degrees Celsius. During solar flares, the temperature of corona can reach beyond 10 million degrees Celsius.
19. Interestingly, sun’s magnetic field is only 2 times stronger than that of Earth! But, the magnetic pull becomes highly concentrated in smaller areas and can increase up to 3,000 times the magnetic pull of Earth. This weird magnetic field is caused by it unusual spins. At the equator, sun spins more rapidly compared to rotation speed found at higher latitudes. The inner parts of the sun, i.e. its core and its radiative zone rotate at higher speeds than the surface. This produce sunspots, solar flares and coronal mass ejection.
20. Solar flares are extremely violent. In fact, they are the most violent eruptions found in entire solar system. Coronal mass ejections on the other hand are extremely massive but less violent. One coronal ejection and throw out nearly 20 billion tons of mass into open space! Sunspots on the other hand are cool spots on the surface of sun. They are nearly circular in size. There are magnetic field lines bundled densely inside the sun. When these bundles break through the surface, these sunspots appear. The maximum number of sunspots found in a cluster can be 250 and the minimum is zero (0). These sunspots keep changing from 0 to 250 and then back to 0. This is known as a solar cycle and takes about 11 years to complete. When a solar cycle is completed, it is marked by rapid reversal in the polarity of the magnetic field.