The Sun – Nearest Star
Sun is one of the most studied astronomical bodies in our solar system, and, for very obvious reasons, has held the attention of a vast number of physicists and scientists. The amount of research that has gone into the understanding of our Sun and its working has been enormous and revolutionary, especially since the digital age took over, providing visual access to some of the most intricate phenomena that could only be thought of before through equations.
We are very near, yet far to understanding the fundamental reactions that occur in the very heart of the Sun. Our planet’s different layers have well-defined boundaries above and below which the behaviour changes predictably. Though our current technologies are yet to advance into providing us with the answers to some of the more fundamental questions, a significant part of our planet is known to us, enough to safely bet on the future patterns.
The Sun, on the other hand, is providing us more questions than answers. It is entirely comprised of what we now call plasma, the fourth state of matter. A place where electrons are stripped away from the atoms and the light produced from the nuclear reactions spends more time finding its way towards the surface than travelling through the interstellar medium, the Sun proves to be more and more counter intuitive as we try to delve further.
One of the most intriguing questions, however, is the working of the Solar Dynamo. The process residing at the heart of the Sun has been fuelling the Sun’s magnetic fields since the beginning of time. With the basic function of converting kinetic energy to electric and magnetic energy, this dynamo is responsible for the self-sustaining magnetic fields.
With the different layers of the Sun rotating in different directions (the equator rotates faster than the poles, much to the fury of the magnetic fields), the movement of the plasma is very turbulent, causing the magnetic fields to twist and turn into tight helical structures. As they emerge through the surface, these twisted fields form Sunspots (those dark spots on the surface of the sun). The high intensity of the magnetic fields makes the sunspot area quite cool as compared to the surrounding surface (thus the dark spots).
All this occurs during the 11th year (solar maximum) of the solar cycle, when, the magnetic poles of the Sun are on the verge of a reversal. When the plasma movement makes the helical structure into something incomprehensible, the gravity lets go and the plasma is flung into space by a process known as magnetic reconnection. What is that is thrown into space? Not the magnetic field. Not the plasma. Instead, the magnetic field lines are frozen into the plasma! Which is why whenever you look at the plasma flinging out into space for a short duration of time, you can see it forms a loop. These loops form poles and it is when these poles overlap due to the strange motion of the sun, that they break. Even stronger solar winds are also caused when two such loops crash into each other.
Together, they start their journey into the solar system.
These ejections occur all the time, even more so during the solar maximum. Since the plasma is ejected from the corona of the Sun, these jets are named as Coronal Mass Ejections(CME).
The relative drop in temperature and pressure expands the CME to thousands of kilometres. They travel to the interstellar medium, through planets and stars, asteroids and rockets, until they are completely absorbed.
When unfortunate enough to be in the path of a CME, Earth is quite frequently bombarded with these ejections. Our magnetic field, powered by its own dynamo, is our saviour. We really do owe our existence to the magnetic field. It is the one that stops the charged particles in the CME from showering upon us. Since our field is weak at the poles, these particles travel all the way towards the poles and enter our atmosphere, colliding with oxygen and other elements present in the air. The energy of CME is transferred to oxygen, neon and other elements which are then excited to higher energy levels. It is when these electrons return to their ground state, that we see the beautiful display of colours in the sky, popularly known as Northern Lights or Aurora Borealis.
One of the primary reasons for the absence of life on Mercury and Venus is their nearness to Sun and the absence of an adequate magnetic field if any. These planets, unlike Earth, are believed to be having a solid core. Earth’s liquid iron core is the basis for our magnetic field. Its motion, just like the sun’s dynamo is primary for the existence of the magnetic field. Our planet is located at just the right distance with just the right atmospheric conditions and magnetic field to survive and make our mark in the cosmos.
The Ultimate Source of Energy
We all need the energy to do work. For walking, running, doing daily tasks and everything, all require energy. You can say that the creator of the Universe has provided us with the specific amount of energy in the form of the sun to us. All energy that we see doing on earth is directly or indirectly came from the sun.
We eat food and do various works, that food or plant requires sun’s energy to perform photosynthesis. The electricity which we use daily at our homes also indirectly comes from the sun. Sun gave potential energy to the water and which we convert it to kinetic energy and then to electrical energy at dams.
So ultimately, all energy that we see on earth, directly or indirectly came from the sun.