A new view of the Sun from space

Artificial Satellites are providing new tools for the observation of our star. The European Space Agency, ESA, in cooperation with NASA has programmed and developed three important space missions: SOHO, ULYSSES, and CLUSTER which offer new opportunities to study the Sun and how it influences the Earth's environment. SOHO in particular, thanks to an unprecedented stability together with a very complete set of instruments, has responded to several of the most fundamental questions concerning the behaviour and the running of our star. It is now possible to probe its interior down to the very core where the thermonuclear reactions occur and to deduce the physical conditions which exist therein. It is also possible to understand better the origin of the solar wind and why is the solar corona so hot. These two questions have been at the core of a large number of observations and theoretical studies for a long time. Thanks to ULYSSES which observes the Sun from a unique vantage point, outside the ecliptic plane where the orbits of all the planets are located, it is now possible to measure the extension of the solar magnetic field in the interplanetary medium and to observe the 3-dimensional geometry of the solar wind. The 4 CLUSTER satellites in orbit above the poles of the Earth, offer a complementary tool to study the influence of solar activity on our planet and how it affects all electronic, telecommunication devices and other elements on which our modern civilisation rest. These results will be presented with a large number of illustrations and animations which open a spectacular view on our fascinating star, the Sun.