Here, the solar wind, which pushes out toward interstellar space, collides with the interstellar wind, which pushes in towards the Sun.
The first three-dimensional map of the boundary between our solar system and interstellar space–a region known as the heliopause.“Just as bats send out sonar pulses in every direction and use the return signal to create a mental map of their surroundings, we used the Sun’s solar wind, which goes out in all directions, to create a map of the heliosphere,†said Reisenfeld.
They did this by using IBEX satellite’s measurement of energetic neutral atoms (ENAs) that result from collisions between solar wind particles and those from the interstellar wind. “The solar wind ‘signal’ sent out by the Sun varies in strength, forming a unique pattern,†explained Reisenfeld. “IBEX will see that same pattern in the returning ENA signal, two to six years later, depending on ENA energy and the direction IBEX is looking through the heliosphere.Reisenfeld’s map shows that the minimum distance from the Sun to the heliopause is about 120 AU in the direction facing the interstellar wind, and in the opposite direction, it extends at least 350 AU, which is the distance limit of the sounding technique. For reference, the orbit of Neptune is about 60 AU across.
June 13, 2021June 13, 2021June 13, 2021