Spacecraft Missions (cont.) SOHO (Solar & Heliosphere Observatory) was launched on December 2, 1995. It is a cooperative effort between the European Space Agency (ESA) and the NASA. SOHO is designed to study the internal structure of the Sun, its extensive outer atmosphere and the origin of the solar wind, the stream of highly ionized gas that blows continuously outward through the Solar System. The images from SOHO have been spectacular. SOHO is helping us understand the dynamic interactions between the Sun and Earth's magnetic environment. Its legacy will enable scientists to solve some of the most perplexing riddles about the Sun, including the heating of the solar corona, the acceleration of the solar wind, and the physical conditions of the solar interior.