Abstract While extensive use of the passive is shown by frequency counts of verb tense and aspect which are performed on corpora combining texts from a variety of scientific and technical fields, significantly different results may be obtained when one compares the frequency of the passive and active voices within a single scientific or technical field. In this paper we examine the frequency of the active and passive verb forms in two astrophysics journal articles, finding that we plus an active verb occurs at least as frequently as the passive in both articles. On the basis of consultation with an informant in astrophysics, we propose four rhetorical functions of the passive as opposed to we plus an active verb: (1) we indicates the author's unique procedural choice, while the passive indicates an established or standard procedure; (2) we is used to describe the author's own work and the passive to describe the work of others, unless that work is not mentioned in contrast to the author's, in which case the active is used; (3) the passive is used to describe the author's proposed studies; and (4) the use of the active or the passive is determined by focus due to the length of an element or the need for emphasis.