The Kennedy Space Center is experiencing unusual activity. After the successful take off Monday morning, the shuttle Endeavor last part deliver large components of the International Space Station, NASA will launch on Wednesday afternoon (16 h 26 French time) on board a Atlas 5 rocket, satellite Solar Dynamics Observatory (SDO), to better understand the activity of our star and its impact on the Earth and its climate.

Scheduled to last five years, this mission will cost 848 million dollars (620 million euros), starts when the Sun finally gives signs of awakening after a long period of lethargy, "the famous Sun its way off of the SDO, "says astrophysicist Stephen Pariat who will participate with his team at the Paris Observatory (LESIA / CNRS-Université Pierre et Marie Curie-Université Paris Diderot), analysis and interpretation of data gathered by AIA (Atmospheric Imaging Assembly), one of three scientific instruments SDO.

A prolonged period of inactivity

Solar activity is punctuated by cycles of about 22 years. During the first half, our star is the site of increased activity manifested by flares and CMEs often spectacular, but decreased gradually during the second half. When he arrived at a minimum, the Sun no longer has any dark spot on its surface, indicating that its magnetism, and thus its activity are at their lowest.

For two years, astronomers expect to see our planet begins a new cycle, surprised his long sleep, to the point of wondering if he would wake up one day! This was not the first time between 1645 and 1715, when the mini-Ice Age, when Europe and North America have suffered very severe winters, the sun has experienced a period of prolonged inactivity without that it can be said, provided that the two phenomena were linked. But the 19 and 20 January, five M-class flares, the strongest recorded since 2008, have finally reassured the scientific community.

On top of its orbit géosynchronisée approximately 35 000 km altitude, SDO should determine the duration of the next cycle of the sun, whether changes in its business or otherwise affect Earth's climate, and to see if is possible to predict when violent solar winds of charged particles to high energy strike our planet. These winds can disrupt satellites, power distribution systems, and endanger the health of astronauts going into space.

Successor of the European satellite SOHO, launched ago fifteen years, SDO will observe the Sun continuously with a spatial and temporal resolution much higher. Thus the instrument AIA transmit images of the solar atmosphere out of ten wavelengths every ten seconds.