Boundaries of the heliosphere

The sphere of influence of the Sun, or heliosphere, is carved out by the solar wind – a stream of charged particles emitted by the Sun continuously.

The heliosphere expands well beyond the outer fringes of the Solar System where it meets material (dust, gas and cosmic rays) of interstellar origin and interacts with it. The ESA/NASA Ulysses mission was the first to perform direct measurements of interstellar dust and gas, and studied galactic cosmic rays in unprecedented detail.