The Sun as never viewed before



With the launch of the Solar and Heliospheric Observatory (SOHO), on December 2, 1995, solar physics entered a new era of “viewing” the Sun and heliosphere without interferences from the Earth's atmosphere. SOHO is a mission of international cooperation between the European Space Agency (ESA) and NASA. The most exciting new discoveries from SOHO include the unexpectedly high magnetic activity observed during the very minimum of the solar cycle and the “observation” of the interior structure of the Sun (helioseismology). The coronal instruments are showing that coronal mass ejections (CMEs) leave the Sun more frequently than expected, at the rate of approximately one per day. The helioseismology experiments, with their extremely low noise due to the absence of the Earth's atmospheric interference, are showing that convective cells under the solar surface are shaped like pancakes, not spheres as was previously assumed.