Professional vision has become a key concept for the study of expertise. This paper celebrates the sophistication of Charles Goodwin's (1994) formulation of the concept by specifying a form of professional vision, rather than relying on its coinage to do the work of analysis. Video of a public astronomy education session in a Portuguese observatory shows how the astronomer instructs a young boy to recognize sunspots against the background of the Sun. The astronomer is unable to see what the visitor sees; yet he can explain the visitor's observation, which he does through a question and answer sequence. We call this practice of making astronomical sense of observations “seeing by proxy”. Seeing by proxy specifies professional vision as a cultural method of instruction. It particularizes professional vision as a praxeological not a conceptual matter.