The Voyager 1 and Voyager 2 probes, launched by NASA in 1977, crossed the heliopause and detected a region of plasma with temperatures between 30,000 and 50,000 kelvin. This zone marks the limit of the heliosphere, where the solar wind meets the interstellar medium. The probes’ instruments identified the abrupt increase in particle energy.
Voyager 1 crossed this border in 2012, 121 astronomical units from the Sun. Voyager 2 followed in 2018, 119 astronomical units. Both recorded the phenomenon known as wall of fire.
- Increase in the density of interstellar plasma.
- Higher temperatures than predicted in previous models.
- Unexpected continuity in the solar magnetic field.
Characteristics of the region known as the wall of fire
The heliopause does not form a solid barrier, but an area of dynamic transition. Solar particles collide with galactic particles, generating intense heating. The low density of the plasma explains why the probes were not damaged.
The data shows that interstellar plasma reaches 30 thousand to 50 thousand kelvin. This range exceeds initial estimates of 15,000 to 30,000 kelvin. Low particle collision prevents significant heat transfer.
Composition of the heliosphere and its protection
The heliosphere acts as a magnetic bubble created by the solar wind. It protects the solar system from galactic cosmic rays. Upon crossing the heliopause, the probes observed a reduction in the speed of the solar wind.
The outer region presents denser and colder plasma compared to the interior. However, the transition zone records energy spikes. Measurements confirm that the heliosphere expands and contracts with solar activity.
Voyager 2’s plasma instruments provided direct data. The probe detected parallel alignment in the internal and external magnetic fields.
Data collected by probes in interstellar space
Voyagers continue to transmit information from distances greater than 24 billion kilometers. They measure charged particles and magnetic fields beyond the heliopause.
- Plasma density twice as high abroad.
- Reduction in cosmic rays within the heliosphere.
- Variations in the position of the boundary with solar cycles.
Temperature and plasma density measurements
The probes recorded temperatures of 30,000 to 50,000 kelvin in the transition layer. This energy derives from the compression of particles in the heliopause. Voyager 2 confirmeddata from Voyager 1 on the magnetic field.
Scientists note that the heliopause forms a comet-like tail. Interstellar plasma remains rarefied, with minimal collisions.
Legacy of the Voyager missions in cosmic exploration
The Voyager probes provided the first direct measurements of the interstellar medium. They have been operating for almost 50 years and send valuable data. The discoveries refine models about solar and galactic interactions.
The missions reveal that the heliopause varies in position and thickness. They detect plasma waves and energetic particles. The remaining instruments work despite the extreme distance.
Voyager 1 and 2 remain active in interstellar space. Their data helps understand the protection of the heliosphere against external radiation. Plasma and magnetism measurements continue to reach Earth.
