The Ulysses Map of the Heliosphere

A polar plot showing actual measurements of solar wind speed (linear scale, approx. range 350-800 km/s), magnetic field (polarity), energetic particles and cosmic rays (logarithmic scales, with the cosmic ray trace offset with respect to the lower-energy particles) acquired by the Ulysses experiments. Particularly striking is the uniform fast (750 km/s) solar wind that fills a large fraction of the heliosphere above 30 degrees latitude in both hemispheres. Other noteworthy features are

• the persistence of 26-day periodic variations in the flux of accelerated particles to much higher latitudes than the associated solar wind compressions (best seen in the first half of 1994), and
• the relatively small increase in cosmic ray flux over the poles compared with the equator (as seen in the left-hand side of the plot - the larger increase in 1992-93 is a temporal effect resulting from the transition to solar minimum conditions).

Because of the elliptical nature of the spacecraft orbit, Ulysses traversed the region represented in the left-hand side of the figure much more rapidly than that on the right. This accounts for the difference in appearance of the data traces in 1995 and 1996, for example. Time ticks are shown on the outer circle for reference.

[Courtesy of D.J. McComas / G. Gloeckler / J. Geiss (solar wind speed); A. Balogh / R. Forsyth (magnetic polarity); R.B. McKibben / R. Marsden (accelerated particles and cosmic rays)]