The NASA Interstellar Bundary Explorer, launched in 2008, rotates around the Earth to map the heliopause
The Milky Way is the home of more than 100 billion stars. Our solar system is trapped in a bubble called the heliospherica, which separates us from the rest of the galaxy and protects us from some of the cosmic rays. This protective bubble is created by the Sun itself, which constantly emits a flow of charged particles. This solar wind extends far beyond Neptune and even Coyper's belt, carrying with it part of the solar magnetic field.
The heliosphere was discovered in the late 1950s, and scientists learn more and more about how it reduces radiation effects on cosmonauts and spacecraft and, in general, how stars can affect neighbouring planets, equipped with telescopes to observe the outer edge of the heliospheric, the Interstellar Bundary Explorer, which is formed where the interstellar environment and the solar wind meet.
Boundaries examined by atomic streams
All the main planets of our solar system are located in the inner layer of the heliosphere, where solar wind particles are extremely fast.
The IBEX satellite records ENA, which is formed when the solar wind hits the interstellar wind; although most of these atoms are then catapulted into deep space, some of them return back to the center of the solar system.
Previous heliospheric maps were based on long-term measurements of the evolution of solar wind pressure and ENA emissions," explained researchers in the journal.
A team of scientists led by Astrophysicist Eric Zirnstein of Princeton University used this event to get a more detailed picture of the form of the final shock wave and heliopause.
Using simulations, the team found that the pressure front had reached the final shock wave in 2015, sending a wave of pressure over the heliospherica; when it reached the heliopause, the wave retraced back to the final shock wave, and then encountered a flow of charged plasma that followed the pressure front, causing a real ENA storm in the helium shell.
The team's measurements also show a significant change in distance to heliopause. The Voyager-1 zone crossed the heliopause in 2012 at a distance of 122 astronomical units. In 2016, the team measured that the distance to the heliopause in the direction Voyager-1 crossed was about 131 AE, while the probe was in interstellar space. The same applied to Voyager 2: when it crossed the heliopause in 2018, it was 119 AE. But the measurements made in 2015 in Voyager 2 estimated the distance to the heliopause in about 103 AE.
These results show that the form of heliopause is changing significantly, but scientists do not yet know why.
NASA plans to launch the IMAP probe in 2025. The ENA cameras on this spacecraft have a higher resolution and more sensitive than those on IBEX. "," said researchers. According to them, this should help solve some of the secrets that still surround this strange bubble protecting our planetary system from space.