Ulysses marks a milestone.

The Ulysses spacecraft has completed a lap around the sun, making it the first craft to have orbited above and below the poles. Launched in 1990, Ulysses began its journey sunward 2 years later. As it ventured near Jupiter's orbit, it received a gravitational kick. That kick enabled it to tour the sun's poles in 1994 and 1995, during the quiet phase of the 11-year solar cycle.

Ulysses revealed that the solar wind blows at different speeds in the polar and equatorial regions (SN: 11/19/94, p. 326). In an equatorial region extending to 30 [degrees] latitude, the wind moves at about 350 kilometers per second. A wind of about double that speed dominates higher latitudes in both the north and the south.

Having now returned to the vicinity of Jupiter's orbit, Ulysses will make its second trip around the poles at the turn of the century. This time, the sun will be at the peak of its activity and the simple division between fast and slow winds may no longer hold, says Ulysses project scientist Richard Marsden of the European Space Agency in Noordwijk, the Netherlands.