Thursday, May 10, 2007

The History Of Astronomy - Part 1

Science nowadays is all about the big, the biggest this, the largest that, all discovered using some humongous new instrument. Astronomy is and always has been a leader in this respect, many of the largest scientific instruments ever built have been telescopes of one sort or another, from the stone circles like Stonehenge, which probably acted as primitive astronomical observatories, through the Uraniborg, built by Tycho Brahe the last of the great naked eye astronomers, to the first truly huge telescope the 72" leviathan of Parsonstown and on up to the modern age of optical telescopes of around 10m in diameter (Keck, Gemini, the VLT etc). Of course for large astronomical equipment you only have to look at the enormous radio telescopes available today, such as the VLA or Arecibo.

The primary mirror of the Gemini North telescope, and yes that is a person in the middle.

The question is what next? The consensus in the US and Europe seems to be to continue a triple pronged approach of larger space based instruments across a wide range of the electromagnetic spectrum (especially those regions blocked by the atmosphere), even larger ground based optical telescopes and vastly larger arrays of radio telescopes. The question tax payers are interested in is unsurprisingly, why? These things cost a lot of money, why do we really need them?

A possible next step in optical astronomy: the European Extremely large telescope, with diameter 42m. Car and two people for scale to the bottom left.

Well lets just ignore the philosophical reasoning of whether most of us are interested in exploring the origins of the Universe, and finding our place within it, we'll assume that everyone is sufficiently interested to want to do astronomy. Why do we need to build such large telescopes? This question was raised to me by a student at a school I was giving a talk at and it got me thinking and I think provides a nice way of explaining how the science of astronomy has developed hand in hand with the advances in technology, in fact often driving many of them. In this short series of posts I hope to explain the development of optical astronomy (the bit I'm familiar with), though I should point out that this is not meant to be an exhaustive description I hope it will cover the basics as I see them.