Galileo's telescope reaches 400th anniversary

It is 400 years since Galileo Galilei demonstrated his telescope, which would lead him to make new astronomical observations

...Exactly 400 years ago today, on 25 August 1609, the Italian astronomer and philosopher Galilei Galileo showed Venetian merchants his new creation, a telescope – the instrument that was to bring him both scientific immortality and, more immediately, a whole lot of trouble.