The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
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Exploring our Solar System and unlocking the secrets of the Universe
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Go to topicMaking space accessible and developing the technologies for the future
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Before Ulysses, it was know that two types of solar wind existed: one was the fast kind, considered unusual, and the other was the slow wind which was considered more typical. But no one knew how the solar wind varied with solar latitude.
Ulysses found that the fast wind is not so unusual after all: it is basically present throughout the whole 11-year solar cycle and disappears only at solar maximum. At solar minimum (left panel) the fast wind fans out from the poles to fill two thirds of the heliosphere, blowing at an average uniform speed of 750 km/s (see arrows), much faster than the wind that emerges from the Sun’s equatorial zone at 350 km/s. At solar maximum (right panel) the solar wind is more turbulent and irregular.