It is the brightest celestial body for us Earthlings. Every day rises eastwards and sets in the west. It is large and luminous, it emits a bubbling heat and keeps all organisms alive: it is the Sun, an average star in the main sequence, undisputed lord of the solar system. Here are some curious aspects of the great star that we do not all know.
The sun is really huge. To make a convincing number it contains 99.85% of the total mass of the Solar System. There is the Sun and the planets in comparison are crumbs, even Jupiter and Saturn. Its mass weighs 330,000 times that of the Earth and almost 3500 times that of Jupiter, which alone is larger than all the other planets put together. Not bad right?
The sun is responsible for the formation of our Solar System and probably the planets. Astrophysicists have calculated the age of the star in 4.6 billion years. The Earth, on the other hand, has about 4.4 of them, demonstrating the fact that it was probably formed by gas clouds that followed the formation of the Sun.
The Sun is warm, yet on the surface it has almost terrestrial temperatures: 5500 degrees, the same as the warm core of the earth. But inside the nuclear furnace temperatures reach millions of degrees, so much so that we talk about plasma, that is, fluid particles, typical of these temperatures capable of generating new matter.
The apparent motion shows us the moving sun, but since the elementary years they have taught us that it is the Earth that moves around the Sun. But like all celestial bodies, it too has an orbit and moves around the center of our galaxy. The speed of rotation of the solar system along the Galaxy is crazy: more than 800 thousand kilometers per hour and we complete the full lap every 230 million years.
Most studies on the Sun come from eclipse and direct observation. Only in recent years have we shipped specific probes to study it, which have provided valuable information on the composition of the surface and inner layers. The eclipses made it possible to observe the crown. Since Galileo's time, direct observation has made it possible to identify the sunspots and study their cycle. The most famous probes are SOHO and Ulysess.
The sun is responsible for sending on earth subatomic particles known as neutrinos, which, as many know, have the particular quality of penetrating every body, producing no physical or chemical reaction. At the same time, the solar wind is made up of particles with positive or negative charge (i. e. electrons and protons) which have a considerable influence on the surrounding bodies, extending the solar magnetic field to its extremities. On Earth the radiation is bent by our magnetic field, to the point of intersection of the magnetic north pole, creating the suggestive northern aurore. Radiation bleached the United States flag hoisted on the Moon.
The Sun like any other celestial body has a life cycle: currently it is in the so-called main sequence phase, just over half of its path. When its cycle ends, it will mean that nuclear fusion reactions are no longer possible inside it and that all hydrogen and helium atoms will have been converted into heavier elements, becoming a red giant, until collapsing into a white dwarf.
