The Sun, viewed through a clear solar filter

The Sun is a star located at the center of the Solar System and behaves like a giant hot ball of plasma that continuously shines thanks to an internal thermonuclear “reactor.” In this process, it constantly produces energy, which it generously radiates in all directions in the form of light, heat, and a small amount of ultraviolet radiation, like a cosmic lamp with a very serious budget. For Earth, the Sun serves as the main energy supplier — without it, the biological system would look significantly less optimistic. It is not surprising that in different historical periods it was even considered a deity: it is difficult not to grant cult status to an object that literally enables the existence of all life.

Despite its local importance for Earth, the Sun has a rather modest “address” on the scale of the galaxy: it orbits the center of the Milky Way at a distance of approximately 24,000–28,000 light-years, meaning it is located in a quiet peripheral region of a vast cosmic system that is not even aware of all human disputes about it. From Earth, the Sun is about 1.496×10⁸ km away — or roughly 8 light-minutes — which means we always see it with a slight delay, as if it is a little late for its own light show. This distance is so stable and useful that it became the basis for the astronomical unit — a universal scale of measurement within the Solar System. In terms of size, the Sun looks quite impressive: its diameter is about 109 times larger than Earth’s, and its mass accounts for about 99.86% of the total mass of the Solar System. In other words, almost the entire system is concentrated in a single object, while the rest are just additional details for variety.

Its outer layer, the photosphere, is composed mainly of hydrogen (~73%) and helium (~25%), elements that behave quite calmly unless forced into thermonuclear processes. In the Sun’s core, these processes continuously convert about 600 billion kilograms of hydrogen into helium every second, while approximately 4 billion kilograms of matter per second are converted into energy — which looks like a very efficient but slightly overpowered power-generation system. The Sun formed about 4.6 billion years ago, when a large molecular cloud of matter decided not to remain scattered and, under the influence of gravity, collapsed into a dense and extremely hot object that “turned on” nuclear fusion. Since then, the Sun has been steadily functioning as a G2V main-sequence star — a well-balanced but extremely powerful system that is not planning to shut down anytime soon.