The name SWAN stands for Solar Wind ANisotropies. This instrument, a collaboration between the Service d'Aéronomie and the Finnish Meteorological Institute, is one of the twelve instruments on board SOHO (SOlar Heliospheric Observatory) satellite. The Service d'Aéronomie scientific group was responsible for the hydrogen cells development and construction, as well as for the periscope mirror system.(See the Instrument section of this site.)

SOHO was launched to the L1 Lagrangian point between the Sun and the Earth 1.5 x 10⁶km ahead of the Earth on 2 December 1995. SWAN was switched on for the first time on 7 December 1995 but without switching on the HV of the detectors. After a 10-day period of several stabilization tests, the first light was seen by the instrument on 16 December 2005. Ever since, the instrument has been providing almost constantly the scientific community with daily observations of the sky in Ly-α.