On October 4, 1957, the Soviet Union launched Sputnik 1 into Earth’s orbit. The beach-ball-sized satellite weighed just 83 kg and rode an R-7 rocket from Baikonur Cosmodrome.

Sputnik 1, meaning ‘fellow traveller’ in Russian, broadcast a continuous beep-beep signal. Radio telescopes around the globe picked it up, confirming its presence in orbit.

The launch shocked the world and sparked the space race between the US and the USSR. It opened a new era of scientific innovation and international competition that led to human spaceflight.

October 4 also marks other milestones. Pope Gregory XIII introduced the Gregorian calendar on this day in 1582, correcting a 10-day drift from the older Julian calendar.

And on October 4, 1958, France ratified the constitution of the Fifth Republic, reshaping its politics under Charles de Gaulle.

The satellite orbited Earth for three months. Its radio signal inspired a generation of scientists and engineers around the world.