Date: 13 Jan 1996
Satellite: SOHO
Depicts: Time Averaged Dopplergram
Copyright: SOHO/MDI (ESA/NASA)

The resulting image clearly shows the supergranulation pattern. The "smooth" area in the center is where the supergranules do not contribute to the signal since what observers see are horizontal motion and MDI measures only the component of motion directed towards or away from SOHO. (Note that supergranules are convective cells, so their motion is convective, but they are on a much larger scale than granules, and observers usually see mostly the horizontal motion.) Close inspection shows that the supergranules flow outwards from their centers so that the edges towards the center are dark (motion toward SOHO) and the edges towards the Sun's limb are bright (motion away from SOHO). These flows are about 400 metres per second. SOHO will allow a detailed study of such large scale convective motions.