much larger than the central source—they change in structure over several days. The changes occur because the jets are hurling material at over a quarter of the speed of light. The material is moving fast enough and the object is close enough for us actually to observe changes in distribution over short periods of time.
    There is a great deal of “noise” in this image, not related to SS433 (most of the amorphous blue objects around the edges, for example). Some is caused by the background activity of W50, some by the instrument used to observe it.