Thanks to this precise discovery, we will be able to better understand the environment of the solar system and how it interacts with interstellar space. Remember that the heliosphere is a protective bubble created by the solar wind and is made up of a stream of protons, electrons, and alpha particles.
It extends from the sun to the interstellar space and it is what allows us to protect the Earth and our solar system from interstellar radiation. That said, by being able to map the boundary of the heliosphere, scientists can better understand how the interstellar and solar winds interact.
It should be mentioned that physical models have been theorized about this limit for a long time. But this is the first time that scientists managed to measure the limit and build a three-dimensional map of the heliosphere. For this the researcher Dan reisenfeld Los Alamos National Laboratory and a team of scientists used data from NASA’s IBEX (Interstellar Boundary Explorer) satellite, in Earth orbit.
It should be mentioned that it is this satellite that detects the particles from the heliosphere, the boundary layer between the solar system and interstellar space. Thanks to this, the team was able to map the edge of this area, that is, the region known as heliopause. It is precisely in this region that the solar wind that goes out into interstellar space collides with the interstellar wind that pushes towards the sun.
It should be noted that the measurement required the use of a technique somewhat similar to the way bats use sonar. Basically experts make use of the solar wind that emanates from the sun in all directions to be able to draw a map of the heliosphere.
The measurements resulting from the IDEX satellite of the energetic neutral atoms (ENA) arise from collisions between the particles of the solar wind and those of the interstellar wind. It should be added that the intensity of this signal will depend on the intensity of the solar wind that collides with the sheath of the heliosphere. The moment a wave hits the sleeve the ENA count increases and the IBEX can detect it.
According to Reisenfeld, the solar wind signal sent by the sun varies considerably in intensity, thus forming a unique pattern. This same pattern will be reflected in the IBEX in the ENA signal that returns, after two to six years later. It should be added that this is the time form in which the distance of the region from the ENA source is in a given direction.
Although it should not be overlooked that time will depend on the energy of the ENA and the direction in which the IBEX is looking through the heliosphere. This is the method that was used to build a 3D map, making use of the data collected throughout the solar cycle, specifically from 2009 to 2019.
Regarding the fact that it takes so long to return the signal to the IBEX, this is due to the great distances involved. Recall that the distances of the solar system are measured in astronomical units (AU). With this system, 1 AU corresponds to the distance from the Earth to the Sun.
On the Reisenfeld map it can be seen that the minimum distance from the Sun to the heliosphere is about 120 AU in the direction facing the interstellar wind and in the opposite direction. So it ends up covering at least 350 AU, this being precisely the distance limit for the probing technique.