Scully and Mulder were sent to investigate a series deaths all involving boys from the same high school. They find the town in uproar, rumors of a satanic cult are spreading. Everyone in town seems to be acting slightly out of character, including, eventually, Mulder and Scully.
See HERE and HERE.
The planetary alignment which was stated to be the cause of the problems was between Mercury, Mars and Uranus. The alignment was shown onscreen in the episode and was depicted at night near a full moon. A full moon is always opposite from the sun and so Mercury could never be in a visual alignment with a full moon. Additionally, Uranus is not visible with the naked eye.Dramatic license was obviously in play, but did the episode's writers bother to consult an actual astrologer, I wonder? The 84 years equates roughly to the time it takes Uranus to orbit the Sun, so it's Uranus' party we're dealing with, I guess. On 12 Jan 1979 Uranus was at 20.7 Scorpio, but that doesn't tell us much. It's all about those "additional alignments" happening on the uncertain date of these X-Files events. Crafty scriptwriters!
It was nice to see astrology given a role in an X-Files episode. Not before time! It was all a bit nutty, lots of X-File in-jokes, an episode not meant to be taken too seriously. Whenever astrology manages to edge its way into drama, the only way the writers know to go is "nutty". Pity! Still, I did enjoy the Syzygy episode.