Seeing the Far Side
STEREO-A provides off-angle views of solar activity and coronal mass ejections. Originally part of a pair launched in 2006, it orbits the Sun slightly faster than Earth. Its twin STEREO-B was lost in 2014. STEREO-A continues to complement Earth-based and L1 solar observations.
Mission Timeline
2006-10-25
Launch with STEREO-B on Delta II
2011-02
Achieved 180° separation — first full far side view
2014-10
STEREO-B lost during conjunction
2023-08
Returned to Earth's neighbourhood