Student Article
Does Our Solar System Have a Protective Wall?
Solar wind (noun): A stream of particles from the Sun.
Interstellar medium (noun): The matter and radiation that exist in the space between star systems.
Astronomical unit (noun): The average distance between the Earth and the Sun.
Cosmic rays (noun): Energetic particles from space.
Plasma (noun): A state of matter similar to gas but consisting of charged particles.
Ever wondered if our Solar System has a boundary?
Meet the edge: the heliopause
Our Solar System has a boundary called the heliopause. This is where the solar wind from the Sun meets the interstellar medium, which is the wind of particles from other stars. The solar wind consists of protons, electrons, and alpha particles. The heliopause marks the edge of the heliosphere, the bubble of space dominated by the Sun's magnetic field and particle emissions.
How far out is it?
The heliopause is located about 120 astronomical units (AU) from the Sun in the direction facing the interstellar wind and extends to at least 350 AU in the opposite direction. One AU is the average distance between the Earth and the Sun.
Space force field: why it matters
This boundary is crucial because it deflects about 70% of harmful cosmic rays, protecting Earth and humans from interstellar radiation. NASA's Voyager 1 and Voyager 2 spacecraft crossed the heliopause in 2012 and 2018, respectively. They discovered that the plasma at the heliopause becomes denser and the local magnetic field increases.
Hot but harmless
Just beyond the heliopause, the temperature of the interstellar medium is extremely high, ranging from 53,492-90,032°F (29,700-50,000°C). This region is sometimes called the "wall of fire," but the plasma is so diffuse that spacecraft can pass through it unharmed.
© Dr. Alastair Gunn / Our Media
Solar wind (noun): A stream of particles from the Sun.
Interstellar medium (noun): The matter and radiation that exist in the space between star systems.
Astronomical unit (noun): The average distance between the Earth and the Sun.
Cosmic rays (noun): Energetic particles from space.
Plasma (noun): A state of matter similar to gas but consisting of charged particles.