The heliopause is the boundary where the solar wind from the Sun meets the interstellar medium, which is the matter that exists in the space between stars. This region marks the edge of our solar system, where the influence of the Sun diminishes and the pressure from cosmic rays and other stars begins to take over. Beyond the heliopause lies the vastness of interstellar space, where conditions are very different from those within our solar system. The Voyager 1 spacecraft, launched in 1977, was the first human-made object to cross this boundary, providing valuable data about the nature of space beyond our solar system.