The Halley's Comet Panic of 1910

Real astronomers announced Earth would pass directly through a comet's tail — and people around the world genuinely panic-bought gas masks and "anti-comet pills," convinced they were about to be poisoned from the sky.

In 1910, as Halley's Comet made its periodic close approach to Earth, astronomers correctly predicted Earth would pass through the comet's tail, which spectroscopic analysis had shown contained toxic cyanogen gas. Despite scientists' accurate reassurances that the gas would be far too diluted to cause harm, worldwide public panic ensued, leading to a real, documented wave of gas mask sales and fraudulent "anti-comet" pill scams.

✕debunked

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Quick facts

→In 1910, astronomers accurately predicted Earth would pass directly through the tail of Halley's Comet during its periodic close approach.
→Spectroscopic analysis of the comet's tail had genuinely detected the presence of cyanogen, a toxic gas, generating real scientific interest and, separately, significant public alarm.
→Astronomers at the time correctly and publicly explained that the gas would be so extremely diluted across the vast distance of the comet's tail as to pose no genuine health risk to people on Earth.
→Despite this scientific reassurance, documented public panic occurred worldwide, including real gas mask sales and fraudulent entrepreneurs selling "anti-comet" pills and other supposed protective remedies.

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Halley's Comet Panic of 1910 (event)

Real worldwide public panic over Earth passing through Halley's Comet's tail; astronomers accurately predicted both the gas presence and the complete absence of harm.

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