The day Galileo brought astronomy to the masses

One of Galileo’s first telescopes

By Michael Banks

Today marks an important date in the calendar of the International Year of Astronomy (IYA2009.

400 years ago, on 25 August 1609, the astronomer Galileo Galilei presented his first telescope to policy makers from the Venetian Republic.

Galileo ushered the lawmakers into St Mark’s Campanile – a bell tower in St Mark’s Square — in the heart of Venice to present his latest invention.

Impressed with seeing objects such as ships from a great distance, the telescope obviously left its mark as Galileo’s salary was doubled and he was also awarded life tenure at the University of Padua.

Galileo probably made a lot of cash from selling the telescope to merchants who found them useful at sea and as items of trade.

However, Galileo is, of course, best known for the mark he has left on the history of astronomy. (As always Google have their own tribute to the anniversary)

To mark the IYA2009, earlier this year we published an interesting article about how one of Galileo’s early telescopes was being rebuilt by researchers in Italy to study what Galileo may have been able to see.

Staff at the Institute and Museum of the History of Science in Florence, Italy, together with the Arcetri Observatory, also in Florence built an exact replica of the device that Galileo gave to his patron the Grand Duke of Tuscany, Cosimo II, in about 1610 that could magnify distant objects by up to a factor of about 20.

The Galileo anniversary is, however, not the only one in astronomy on this day.

Today also marks the 20th anniversary of NASA’s Voyager 2 craft coming closest to Neptune on its grand tour of the outer planets. (click here for the article we will be publishing in the September issue of Physics World about the anniversary)

The two Voyager craft — named Voyager 1 and Voyager 2 — launched on 5 September and 20 August 1977, respectively, (yes, the dates are the right way round) and completed their grand tour of the solar system 20 years ago.

Possibly one of the most successful space missions, the two craft are now on their way to the boundaries of the heliosphere – the ‘bubble’ of space blown by the solar wind into the interstellar medium.

So if you are feeling inspired by the Galileo anniversary and want to see for yourself what he could have observed 400 years ago, then you can always get your hands on your very own Galileoscope.