This first telescopic discoveries of the solar system have long been attributed to Galileo Galilei, the Italian who went on to play a leading role in the 17th century scientific revolution. Now astronomers and historians in the UK are keen to promote a lesser-known figure, English polymath Thomas Harriot, who made the first drawing of the Moon through a telescope several months earlier than Galileo, in July 1609.

In a paper to be published in February in Astronomy and Geophysics, the journal of the Royal Astronomical Society (RAS), historian Dr Allan Chapman of the University of Oxford explains how Harriot not only preceded Galileo but went on to make maps of the Moon’s surface that would not be bettered for decades.

Harriot lived from 1560 to 1621. He studied at St Mary’s Hall (now part of Oriel College), Oxford, achieving his BA in 1580 before becoming a mathematical teacher and companion to the explorer Sir Walter Raleigh. In the early 1590s Raleigh fell from royal favour and was imprisoned in the Tower of London.

From this time Harriot was passed to the patronage of Henry Percy, the Ninth Earl of Northumberland who was himself imprisoned as one of the Gunpowder Plotters in 1605 but continued to support Harriot in his residence at Sion (now Syon) Park, in what is now west London. Harriot became a leading force in mathematics, working on algebraic theory and corresponding with scientists in the UK and across Europe.

By 1609, Harriot had acquired his first ‘Dutch trunke’ (telescope). He turned it towards the Moon on 26 July, becoming the first astronomer to draw an astronomical object through a telescope. The crude lunar sketch shows a rough outline of the lunar terminator (the line marking the division between night and day on the Moon, as seen from the Earth) and includes a handful of features like the dark areas Mare Crisium, Mare Tranquilitatis and Mare Foecunditatis.

Harriot went on to produce further maps from 1610 to 1613. Not all of these are dated, but they show an increasing level of detail. By 1613 he had created two maps of the whole Moon, with many identifiable features such as lunar craters that crucially are depicted in their correct relative positions. The earliest telescopes of the kind used by Harriot (and Galileo) had a narrow field of view, meaning that only a small portion of the Moon could be seen at any one time and making this work all the more impressive. No better maps would be published for several decades.

Despite his innovative work, Harriot remains relatively unknown. Unlike Galileo, he did not publish his drawings. Dr Chapman attributes this to his comfortable position as a ‘well-maintained philosopher to a great and wealthy nobleman’ with a generous salary (somewhere between GBP120 and GBP600 per annum or by way of comparison several times the remuneration of the Warden of Wadham College, Oxford). Harriot had comfortable housing and a specially provided observing chamber on top of Sion House, all of which contrasted with Galileo’s financial pressures.

Dr Chapman believes that the time has come to give Harriot the credit he deserves. “Thomas Harriot is an unsung hero of science. His drawings mark the beginning of the era of modern astronomy we now live in, where telescopes large and small give us extraordinary information about the Universe we inhabit.”

Professor Andy Fabian, President of the Royal Astronomical Society, agrees. “As an astrophysicist of the 21st century, I can only look back and marvel at the work of 17th century astronomers like Thomas Harriot. The world is right to celebrate Galileo in the International Year of Astronomy – but Harriot shouldn’t be forgotten!”

The International Year of Astronomy (IYA2009) celebrates the 400th anniversary of Galileo’s use of the telescope. IYA2009 is endorsed by UNESCO and is now supported by 135 countries under the leadership of the International Astronomical Union (IAU).

Throughout the year, thousands of professional and amateur astronomers will be working with the public as part of a global effort to promote astronomy and its contribution to science and culture. A series of innovative projects will encourage public engagement, from observing sessions at observatories to online blogs, photographic exhibitions and the campaign to combat light pollution.

In the UK, IYA2009 is led by volunteers in amateur astronomical societies, universities, industry, museums and science centres and supported by the Royal Astronomical Society, the Institute of Physics and the Science and Technology Facilities Council. The number of events and activities is growing rapidly and a full list can be found on the IYA2009 web site.

The Telescope400 celebration will take place at Syon Park on 26th July 2009, when a programme of lectures and other activities will mark the 400th anniversary of Harriot’s first astronomical observation through a telescope.