PARIS (AFP) – Astronomers around the world are gearing up for three days of intense sky-watching in honour of Galileo, whose observations 400 years ago revolutionised our understanding of the cosmos.

The "Galilean Nights" promoted by the International Astronomical Union (IAU) aim at giving hundreds of thousands of people the thrill of looking through a space telescope for the first time.

More than 1,000 public events in over 70 countries are being staged on Thursday, Friday and Saturday nights, according to the website Galilean Nights.

In October 1609 Galileo Galilei began observations with a two-lens telescope that eventually led him to discover the four main satellites of Jupiter and realise that Earth's Moon was pitted with craters and not a perfect sphere.

These and other discoveries led Galileo to conclude, like Nicolaus Copernicus, that Earth revolved around the Sun and not the other way around.

He was persecuted for heresy by the Vatican and forced to recant. The last ten years of his life were spent under house arrest.