His tail swept down: the tail is like that of a crocodile. The verb translated swept (down) is the one used in John 21.8 of the disciples dragging to shore the net full of fish. So another way of saying this is “drag down.” The phrase may then be expressed as “He used his tail to drag down….”

A third of the stars of heaven: as in the case of the first four trumpets (8.7-12) and the sixth trumpet (9.15, 18), the destruction here affects one third of the total. Caird remarks: “The stars are angelic representatives of pagan powers.” See 8.7 on the translation of third.

And cast them to the earth: see Dan 8.10. These stars are thrown down from their exalted position. Cast them indicates an action where the tail propels the stars down to the earth violently.

The rest of the verse is, as Revised Standard Version shows, quite redundant. In some languages it may be deemed unnecessary to repeat who was about to bear a child or to say literally when she brought it forth. Something like the following can be said: “The dragon stood in front of the woman in order to devour her child as soon as it was born.” If in some languages there is no neuter term to refer to an unborn child, whose sex is not yet known, it is possible to say “her son,” as the next verse specifies.

Quoted with permission from Bratcher, Robert G. and Hatton, Howard A. A Handbook on The Revelation to John. (UBS Handbook Series). New York: UBS, 1993. For this and other handbooks for translators see here .