Every 76 years, a cosmic wonder visits sky—Halley’s Comet, a symbol of the persistent human quest to explore and understand the universe. Halley’s 1986 return, on November 10, was a moment that united science, global collaboration and historical fascination. Although it was the least favourable sighting in two millennia—Earth and the comet were positioned on opposite sides of the Sun, making it difficult to observe—Halley’s 1986 apparition became a landmark in universe exploration, spurring development that continue to form our understanding of the cosmos.
This less-visible vision became an opportunity for innovation, as astronomers pivoted from visual observation to scientific analysis. The journey began with astronomer Stephen James O’Meara, who detected Halley through a telescope atop Hawaii’s Mauna Kea in January 1985. Halley’s distant orbit made it difficult to see even from bucolic areas, but this early sighting set the stage for one of the most substantial global scientific collaboration of the 20th century—the "Halley Armada."
An array of space agencies united to study the comet at close range, launching a fleet of probes to capture data and images from several angles. The Soviet Union’s Vega 1 probe took the first-ever images of Halley’s nucleus in March 1986, followed by the Vega 2 probe, which collected additional close-up data. A week later, Europe’s Giotto probe achieved the closest flyby, revealing detailed images of the comet’s dark, occasionally molded nucleus. Japan contributed two probes, Suisei and Sakigake, which added critical insights on the comet’s structure and composition. These missions transformed Halley’s 1986 visit into a milestone in cometary science, capturing data that deepened our knowledge of comets’ volatile makeup and provided humanity’s first glimpse of a comet’s inner core.
This collaboration underscored the power of global cooperation in space exploration. The coordinated missions expanded the scope of knowledge beyond what any single country could achieve alone, uniting scientists globally in a common quest. This effort laid the basis for future scientific corporation and demonstrated that, in the cosmic unknown of space, the combined expertise of many can unlock discoveries otherwise out of reach.
