The Ulysses spacecraft was launched in October 1990 from the space shuttle Discovery on a joint mission of NASA and the European Space Agency. Ulysses makes observations of the solar wind, magnetic field, solar energetic particles, and cosmic rays. Each pass over a pole reveals new information and can be compared to previous passes.

Ulysses has flown over the sun’s Polar regions three times, in 1994-95, 2000-01, and 2007. Now Ulysses is flying over the North Pole at an important time, during the beginning of a new 22-year solar cycle.

The sun’s poles are central to the 11-year ebb and flow of solar activity. When sunspots break up, their decaying magnetic fields are carried toward the poles by huge currents. The old magnetic fields sink beneath the polar surface about 124,000 miles deep, down to the sun’s inner magnetic dynamo that generates the sun’s magnetic field. The dynamo action amplifies the fields and the energy is used in future solar cycles.

The temperature of the sun’s North Pole measured about 80,000˚ Fahrenheit, which was 8% cooler than the South Pole. The polar wind was different too. At the poles, the magnetic field opens up and allows solar atmosphere to stream out at a million miles per hour. Before the polar wind was spilling down to its equator, now it only goes to about 45° latitudes.

During the first Ulysses orbit, the sun’s magnetic poles were positive at the north with outward fields and negative in the south with inward fields. During the second orbit at sunspot maximum, the polar fields disappeared and reappeared with the poles reversing their charges. North became negative with and inward flow and south became positive with an outward flow. Their strength was only half of what they were during Ulysses first orbital pass.