The Jupiter Effect — the planets lined up and nothing fell

In the United States, in 1974, two young astrophysicists named John Gribbin and Stephen Plagemann published a slim book called The Jupiter Effect, in which they argued that a rare alignment of the planets in March 1982 would set off a chain of solar and seismic disturbances culminating in a catastrophic earthquake on California’s San Andreas Fault — an event some readers took to mean the destruction of Los Angeles. The book became a bestseller. The alignment came and went in March 1982 without any unusual earthquake, and well before the date the authors had already begun to back away from their own claim. Gribbin later wrote that he was “sorry I ever had anything to do with it.”

The prediction was not the work of cranks. Both authors held doctorates from Cambridge; Gribbin had trained as an astrophysicist and worked as an editor at the journal Nature. They dressed an apocalyptic forecast in the vocabulary of mainstream science — orbital mechanics, sunspot cycles, tidal stress, fluctuations in the length of the day — and that respectable packaging carried the idea far beyond the audience any street-corner prophet could reach.

The mechanism they proposed was a long causal chain. When the planets gathered on one side of the Sun, they reasoned, the combined gravitational tug would disturb the Sun, increasing solar activity; the resulting solar wind would alter Earth’s weather and minutely slow the planet’s rotation; and that jolt to rotation would trigger earthquakes along faults already under strain. Each link sounded plausible in isolation. The chain as a whole multiplied small, speculative effects into a continental catastrophe.

By the time March 1982 arrived, the case had collapsed under scrutiny. Seismologists pointed out that the planets would not truly align, that their combined tidal pull on Earth was negligible, and that a closer grouping in the year 1128 had passed without incident. In a 1982 follow-up the authors conceded the prediction had failed, then argued — implausibly — that the “effect” had already happened in 1980 and caused the eruption of Mount St. Helens. It is a textbook case of a scientific-sounding doomsday that never had the physics to stand on.