1. THE SOLAR SYSTEM
Our home, the Earth, orbits a star known as the Sun, and is the third planet of our Solar System. The Sun itself, along with approximately 100 billion other stars, makes up a galaxy called the Milky Way. On the other hand, this galaxy is only one of the billions of galaxies comprising the Universe. The circumstances of how the Universe was born remain shrouded in the mists of the distant past; current analyses offer only theoretical assumptions about this early period. The most widely accepted explanation for the origin of the Universe is the so-called Big Bang, which is believed to have occurred about 13.7 billion years ago. According to analyses, this theory is based on the fact that the galaxies, observed in all directions at distances of at least 10 billion light-years around us, are moving away from each other. The Big Bang theory is also supported by the cosmic background radiation detectable with microwave radiometers. It is believed that in the first few minutes following the Big Bang, only the most elementary particles known today – quarks and photons – were present in space. A few minutes later, protons, neutrons, and electrons began to form from these particles. Initially, lighter elements such as hydrogen and helium came into being, followed later by heavier ones.
Over time, gas and dust clouds formed from these particles – an interval which, according to analyses, spanned from several hundred thousand years to about one billion years after the Big Bang. Due to gravitational effects these gas and dust clouds began to condense and merged into distinct clouds, from which – during a period estimated to range from about one billion to about four billion years after the Big Bang – the so-called protogalaxies emerged. Within these protogalaxies, gases and dust clumped together into dense accumulations, forming protosolar disks. Once the density and mass of these disks reached a critical threshold, they ignited to form stars – celestial bodies capable of emitting their own light and heat. The stars observable in the surrounding galaxies are the result of these processes.
Our Solar System is located on one of the spiral arms of the galaxy called the Milky Way, moving through space at an estimated velocity of 215 km/s. Regarding its formation, a number of scientific theories have been developed seeking to explain how this complex system came into being.
The Laplacian theory – which was presented by Laplace himself in one of his popular works – envisioned the entire Solar System as initially being a massive, rotating, high-temperature body. As it cooled and contracted, its rotation accelerated, and upon reaching a critical value, a ring – similar to Saturn’s ring – formed at its edge. From this ring, the planet corresponding to that orbital path emerged. This phenomenon was thought to have repeated until all the planets were formed. […]
According to Kant’s concept, the material of the Solar System originally consisted of a cloud of meteorite
