One astronomical event that was not known to humans before the advent of the telescope is the discovery of moons orbiting other planets. Prior to the invention of the telescope, our understanding of the solar system was limited to the naked-eye observations, and the existence of moons around other planets was unknown.
The first discovery of a moon orbiting another planet came in 1610 when Galileo Galilei observed four large moons around Jupiter using his newly developed telescope. These moons, now known as the Galilean moons (Io, Europa, Ganymede, and Callisto), were previously unseen by human eyes. This groundbreaking observation revolutionized our understanding of the solar system and provided evidence to support the heliocentric model proposed by Copernicus.
The discovery of these moons around Jupiter was a significant astronomical event as it challenged the prevailing belief that all celestial bodies revolved around the Earth. It opened up new possibilities for understanding the dynamics and structure of the solar system.
Since then, the discovery of moons orbiting other planets has continued. With the advancement of telescopes and space exploration, we have discovered numerous moons around planets in our solar system and even around some exoplanets outside our solar system. These discoveries have expanded our knowledge of planetary systems and the diversity of celestial bodies in the universe.