American scientists from the Los Alamos National Laboratory have been able to map the border regions of what we call the heliosphere (this is the area around the Sun, a kind of bubble that separates our solar system from interstellar space). The solar winds rage inside the heliosphere, but at its boundary they are balanced by the pressure of the interstellar wind, creating a conditionally neutral region called the.
The main source of data on the boundaries of the heliosphere was the IBEX spacecraft, whose task was to study the behavior of solar winds in collisions with the interstellar medium. IBEX collected information from 2009 to 2019 – during the full solar cycle. Since the distance to the boundaries of the heliosphere is, by definition, very large for simple devices, and the way there will take too long, the main object of research has become energetically neutral atoms.
This is very similar to the principle of sonar, when the researcher determines the distance to the object from the behavior of the reflected signal. In this case, the solar wind hits the interstellar wind, which generates a by-product – those same energetically neutral atoms. They return within 2-6 years, depending on their energy and direction of movement, which is recorded by IBEX. It creates a complex fancy pattern, from which the heliopause map is formed.
As a result, scientists have established that the nearest boundary of the heliosphere passes at a distance of 120 astronomical units from the Sun. The distant one stretched as much as 350 astronomical units. And although the name itself implies that this area should have the shape of a sphere, in practice it is rather a complex polyhedron.