Ulysses solar orbit. Artwork of the orbit (orange line) followed by the solar spacecraft Ulysses. In 1990, Ulysses was launched from Earth (lower centre) to study the Sun and its solar wind outside the ecliptic orbital plane of the planets. It attained a polar solar orbit by swinging around Jupiter (centre right) in 1992. It passed over the north and south poles of the Sun (red-yellow) in 1994-5, at a minimum period of solar activity, observing a stable and fast polar solar wind. A second set of polar fly-bys, during 2000-1, studied the more variable winds during the solar maximum. Ulysses is a joint ESA and NASA mission.