What human being cannot see can exist: a message from recent studies of solar-terrestrial relationships

Without the Sun, there would be no life on the Earth. Life was created on this planet in such a way that it "matches" with the natural environment and was further evolved through the physical/chemical processes, which reflect the state of the planet. This paper demonstrates that because of the existence of two barriers the Earth possesses, i.e. the atmosphere and the magnetic field, we are peacefully sitting on this planet and are not aware everyday of a number of potentially dangerous episodes that are taking place only 100 km above the Earth's surface. The aurora in the polar sky is one of the visible manifestations of the variability of the solar-terrestrial environment. It is imperative to realize, however, that what we cannot see by human eyes does not mean that they do not exist in reality. For example, during the solar declining phase in terms of visible indicators, such as sunspots on the Sun, geomagnetic activity resulting from invisible activity in the solar corona reaches a peak.