The continuous jets of Cygnus X-1

A resolved jet-like radio-emitting structure on mas scales has been found i n Cygnus X-1. The jet emission is relatively smooth, and does not show the knots and blobs seen in Cygnus X-3. SS433 and GRS1915+105. This suggests th at the jet production mechanism in Cyg X-1 is continuous. with the steady p roduction of the energetic electrons and magnetic field required for the pr oduction of the radio emission. This is unlike the episodic jets seen in th e other sources. The implications of these results for jet formation mechan isms will be discussed.