Photographing the Universe
Marek takes questions after the lecture
The Flamsteed were delighted to welcome back our good friend, Dr Marek Kukula, the Public Astronomer at the Royal Observatory Greenwich, who came to give a ‘behind the scenes’ view about the process that led to the recent ‘Visions of the Universe’ exhibition. The exhibition was an unqualified success, with over 70,000 visitors and some fantastic reviews by the critics.
Marek stated that the exhibition and the broader public programme at the Royal Observatory are designed to communicate the idea that astronomy is deeply embedded in human culture and history.
Turning information from wavelengths right across the electromagnetic spectrum into images that we can see is central to virtually all astronomy. For over 300 years, people have been imaging the sky, either by hand drawing or by photography.
The idea behind the exhibition was to look at the process of imaging and looking at the results of that imaging process, communicating the science that is embedded within the images.
Until the invention of photography, we were limited by what the human eye can see and the skills of the astronomer in drawing the image. It took several decades after the invention of photography for the technology to have advanced sufficiently to allow images to be taken of objects in the night sky. There were several problems to overcome, not least compensating for the continual rotation of the Earth so that long exposures could be taken. Once this was perfected, the camera could be used to record more light coming from the object than can be picked up by the human eye. This meant that far more detail could be recorded as the photographic plates became more sensitive.
The limits of photography using photographic plates was reached by the 1970s, when David Malin perfected techniques to extract the maximum amount of detail from faint low contrast objects. Further advances were not possible as there were limitations in the grain size of particles in the photographic emulsion. It was at this point that astronomers started looking for alternatives – and they started to concentrate on charge-coupled devices or CCDs.
Flamsteed using a Camera Obscure to observe the Sun
Obviously, nowadays, we take these devices for granted as they appear in cameras on our mobile phones. This technology was developed by astronomers in the 70s and 80s and would not have existed were it not for the advances made by astronomy over the last few decades.
Advances in telescopes have also made a huge difference in what we can see in the night sky. Galileo’s telescope could only just resolve that Jupiter was a disc, but this was enough to discover that Jupiter had its own moons. Galileo was also able to observe that Venus had phases, meaning that it had to be closer to the Sun than the Earth. These observations completely changed our model of the Universe and the perception of our place within it.
The use of Camera Obscura technology to project images on to a screen for many people to view became particularly prevalent in the 17th and 18th centuries. John Flamsteed used the camera obscura at the Royal Observatory to make observations of the Sun.