Solar and Heliospheric Observatory Program

The Solar and Heliospheric Observatory (SOHO) Program is a joint ESA–NASA solar observatory launched on 2 December 1995 to study the Sun from its deep interior through the corona and solar wind. ESA leads the mission and NASA provides launch and mission-operations support; repeated extensions have made SOHO the longest-lived Sun-watching satellite and enabled discoveries across two solar cycles, including thousands of comets.