The Sun's Heliopause

Page 45 in "You and the Universe," your personalized fine art book, contains a description of the Sun's "heliopause" and "heliosphere," the latter being the area of the Sun's influence demarcated by the solar wind. Please refer to the glossary for unfamiliar terms that follow.

In addition to light and heat, the Sun continuously emits a million-mph stream of charged particles. This solar wind causes comets’ tails to always point away from the Sun (preceding them as they leave the Sun), disturbs the paths of spacecraft, causes radio interference, the aurora borealis, and power line surges on Earth. As it expands out into space, the solar wind creates a magnetic bubble of ionized gas (the "heliosphere") around the Sun in the rarified hydrogen and helium gas permeating the galaxy between the stars (the interstellar medium).

Where the strength of the solar wind equals that of the collective solar winds of other stars in our galaxy (the interstellar wind) marks the outer border of this bubble. This boundary of the Sun’s influence, the heliopause, separates our solar system from interstellar space. Thought to be about 10 billion miles (three time Pluto’s distance) from the Sun, the heliopause may soon be reached by the Voyagers 1 and 2 launched back in 1977. The orbits of the outer planets, the Kuiper belt, the heliopause, the interstellar wind, and the paths of the Voyager spacecraft are shown in the photograph above.