The hidden synchronicity—and disorder—of the solar system

From mid-March through early April, all five “naked-eye” planets will be aligned across the evening sky. Mercury will hover low but bright in the western twilight, and Venus will dance above it. Mars, Saturn, and Jupiter are higher up, arrayed like a ragged chorus line. A similar apparition will grace the morning sky this December. After that, we will have to wait a dozen years before anything even remotely like this happens again.