We present the first observations of a global coronal wave ( “ EIT wave ” ) from the two Solar Terrestrial Relations Observatory ( STEREO ) satellites in quadrature .
The wave ’ s initiation site was at the disk center in STEREO-B and precisely on the limb in STEREO-A .
These unprecedented observations from the STEREO Extreme Ultraviolet Imaging ( EUVI ) instruments enable us to gain insight into the wave ’ s kinematics , initiation and 3D structure .
The wave propagates globally over the whole solar hemisphere visible to STEREO-B with a constant velocity of \sim 263 \pm 16 km s ^ { -1 } .
From the two STEREO observations we derive a height of the wave in the range of \sim 80–100 Mm .
Comparison of the wave kinematics with the early phase of the erupting CME structure indicates that the wave is initiated by the CME lateral expansion , and then propagates freely with a velocity close to the fast magnetosonic speed in the quiet solar corona .