Bringing Your Faith to Work, Randy Douglass and the late Norman L. Geisler, address the above question:
"The Bible condemns astrology (Lev. 19:26; Deut. 18:10; Isa. 8:19), yet God blessed the wise men (Magi) and seemed to even guide them with the stars to show the birthplace of Christ.
First, astrology is a belief that the study of the arrangement and movement of the stars can foretell events whether they be good or bad. Second, the star (singular) in the biblical story was to announce the birth of Christ, not to foretell it. God gave the star to the Magi to let them know that the Christ child had already been born (Matt. 2:16). Third, there are other instances in the Bible in which the stars and planets are used by God to reveal his desires. The stars declare God's glory (Ps. 19:1-6); creation reveals his existence (Rom. 1:18-20) and will be affected at the return of Christ (Matt. 24:29-30). So the star guiding the Magi was not used to predict, but to proclaim the birth of Christ."1
Courage and Godspeed,
1. Norman L. Geisler and Randy Douglass, Bringing Your Faith to Work, p. 169.