SWAN : Solar Wind ANisotropies
SWAN is used to investigate the solar wind on a very, very large scale. It has helped us to understand where the solar wind is stronger or weaker.
SWAN is also used to examine comets in our Solar System such as the famous Hale-Bopp. The image below shows a huge cloud of gas that surrounded the comet as it approached the Sun. You can just see a small picture of Hale-Bopp in the middle!
Pictures courtesy of the SOHO SWAN consortium.