How a periodic comet once sparked a global panic about the end of life

History · Published 8 October 2026 Swipe more like this →

In short: For millennia, Halley’s Comet was viewed as a celestial omen of destruction or hope. While modern science identifies it as a snowball of dust and ice, its 1910 passage triggered a genuine global panic, as new technology led some to fear the world was about to end.

Known scientifically as 1P/Halley, this periodic comet orbits the Sun every 75 to 76 years. Because it moves in the opposite direction to Earth, its predictable return has allowed astronomers to track it for centuries. In 1705, English astronomer Edmond Halley published 'Synopsis Astronomia Cometicae,' a theory that allowed for the first accurate predictions of the comet's return, making it the first comet whose return could be calculated. This celestial body travels in a highly eccentric orbit. It is a small object with a substantial fraction of its composition made of volatile ices.

Historically, the comet has been interpreted as a powerful omen. Documented sightings date back to Ancient Greece in 466 BCE and to Ancient China in 240 BCE, as recorded in the 'Shiji.' These sightings were thought to influence the monumental decisions of kings, emperors, and rulers, who viewed the comet as a symbol of radical change, destruction, or even good fortune. Such sightings have frequently influenced significant moments of change throughout history. These celestial events have often been viewed as symbols of both destruction and hope.

The physical nature of the comet is quite different from the mythological dread it once inspired. Comets are primitive bodies composed of volatile ices, dust, and rock particles, formed in the cold outer regions of the solar nebula beyond 5 astronomical units from the Sun. As they approach the Sun, these ices sublimate to create a bright atmosphere called a coma and two distinct tails: one of dust and one of ionized molecules. While once feared as a harbinger of doom, Halley's Comet is now a vital scientific tool for studying the primordial solar system. The nucleus is typically only a few kilometres in diameter. This solid core consists of a mixture of silicate and organic dust particles.

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