* Early Observations: People have been observing the Moon since the dawn of humanity. It's a prominent object in the night sky.

* Galileo's Discovery: Galileo Galilei, using his telescope in 1610, was the first to observe and document the four largest moons of Jupiter (Io, Europa, Ganymede, and Callisto). This was a revolutionary discovery, as it proved that not everything revolved around the Earth.

* Continuing Discoveries: Since Galileo, astronomers have discovered countless other moons orbiting planets in our solar system and beyond.

So, it's more accurate to say that:

* Humans have been observing moons since ancient times.

* Galileo Galilei was the first to discover moons orbiting another planet.

* The discovery of moons is a continuous process, with new moons being discovered all the time.