Thomas Harriot: the first telescopic astronomer

I am going to devote the 2007 Christmas Lecture to Thomas Harriot. I think it is appropriate to do so because next year, 2008, will be the 400th anniversary of the invention of the telescope, by Hans Lippershey, Zacharias Jannsen, and perhaps other Dutchmen. And although the principles of the instrument were first made public in 1608, it was at least eight months before anybody recognised that it possessed any scientific potential. For at first, the telescope was used as a military or naval device, or regarded purely as a novelty. As far as we can tell from the historical record, however, it was Thomas Harriot who became the first person to look at an astronomical body through a telescope, on or before 1609 July 26, when he came to realise that the image of the Moon produced by it was very different from what was seen by the naked eye, although he did not publish his discovery.