Starting Saturday evening, you’ll be able to see not one, two or three planets in the night sky, but four. The graphic you see shows the moon's trajectory through the night sky. This means at its peak,

Six planets will form a rare planetary alignment in the night sky on Jan. 21; here is everything you need to know about the 'planet parade' including how to watch it at night.

However, while no such events took place on that date, nor on his revised date of Dec. 25, 1919, the seeds of anxiety and fear of planetary alignments were already planted in the collective human psyche, only to sprout again and again in the decades that followed.