Jet Aircraft Travelling At Transonic Speed

In astrophysics, wherever there is evidence of shocks (standing, propagating or oscillating), the flow close by must be transonic as only supersonic flows form shocks. Interestingly all the black hole accretions are transonic (S.K. Chakrabarti, ApJ, 1996, v. 471, p. 237), many of the flows also have shocks very close to the black holes.
The outflows or jets from young stellar objects or disks around black holes can also be transonic since they start subsonically and at a far distance they are invariably supersonic. Supernovae explosion is accompanied by supersonic flows and shock waves. Bow shocks formed in solar winds around the earth are a direct result of transonic wind from the sun.