During the middle ages if you were to look up at the night sky you would see something very different to the view you see when looking at the sky today. This is partly because the skies are now much bright because of street lights in all but the remote places, but mostly because our understand of the Universe is now so totally different.
The stars would appear as fixed points of light which appeared to never change, only interrupted by the planets meandering slowly through the stars. Occasionally there would be the flash of a meteor, a short-lived shooting star, or something larger falling to Earth. Very rarely a comet might be visible in the sky, and even rarer than that a supernova explosion would suddenly burn brightly in the sky over the period of months or sometimes years. Anything that changed in the night sky was treated with superstitious caution, as being portentous of impending doom. This was largely because people grew accustomed to the regularity of the night sky. The Sun, Moon and planets all appear with a regularity that allowed wealthy people to have Orreries constructed, miniature clockwork versions of the solar system. Comets and supernovae appearances disrupted that order rather like an enraged ex-lover on the Jeremy Kyle show.
400 years ago there was a sort of revolution as Western Europe started thinking about art and science in a very different way, reminiscent of the depth and breadth of scholarship the ancient Greeks had attained, called the Renaissance. Being an astronomer, I would argue that this was kicked off by the ‘invention’ of the astronomical telescope, almost simultaneously by Thomas Harriot and Galileo Galilei, in the early part of the 17th century (the telescope was invented by Hans Lipparshey but Harriot and Galileo were the first who used it for astronomy).
Science changed forever. Galileo observed Jupiter and found that it had moons which orbited the planet itself and not the Sun, or indeed the Earth. He became fascinated with this microcosm and became convinced that the solar system at large was similar with the Sun and the centre not the Earth. Galileo got in lots of trouble for asserting this. This might have been because it was against the official doctrine of the Church and it might have been because he was a bit too forceful in expressing his opinions and made powerful enemies. Either way, that political hot potato meant Galileo found himself under house arrest.
Fortunately Harriot did not suffer the same fate as Galileo, although he was imprisoned in the Tower of London for a brief spell, for seditious activities during the reign of James I. It is a shame he is often overlooked in the history of the astronomical telescope.
Isaac Newton, famous for his theory of gravity, did so much more physics, like his laws of motion, development of calculus and optics. He actually invented a telescope which used a mirror instead of a just lenses which has become the foundation for modern optical astronomy. Telescopes with mirrors can be made much larger than ones which are entirely made out of lenses, and it also makes them shorter than an equivalent refracting or lens based telescope. The largest optical telescope currently envisaged the inventively named “European Extremely Large Telescope” – 39 m
Gradually as people turned more telescopes on the night sky and built better telescopes our understanding of the Universe expanded. There came a point where the telescope became limited by the your observing location. The very early telescopes of Galileo, Harriot and Newton represented a substantial improvement on naked eye observations, but as technology developed to fine tuned the process of constructing a telescope, another problem reared it head.
The atmosphere is rather handy for us as humans because it allows us to breathe, keeps us warm (warmer than space at any rate) and shields us from harmful radiation from the Sun, cosmic rays, small meteors and other things that go bump in the night. So I don’t want to sound ungrateful but it’s a pain in the rear for us astronomers, because the it causes stars to scintillate or twinkle. Its a very similar effect to heat haze, and comes from pockets of the atmosphere continually changing in temperature and density. We call this phenomenon “seeing”, which is a bit of a daft name and open to misinterpretation, like the word “statistics” or the word “quiche”.
The astronomers’ solution to this problem is to take your telescopes up a mountain. This might seem an extreme reaction to something so poetic as the twinkling of stars, but it makes a huge difference to the observations you are trying to make. Remember that astronomy is virtually unique amongst the sciences in that it is almost totally passive. We sit on Earth and collect light because that is virtually all we can do to learn about the Universe. So to be an astronomer you have to be resourceful and extract every gram or millimetre of science from every photon. Only relatively recently have we been able to go into space and the distance that we have travelled is microscopic. We are still a very long way from being able to visit other stars and galaxies, to learn about how they form or take measurements of a Black Hole from close quarters.
So we put our telescopes in strange exotic locations, like up mountains Chile or at the summit of dormant volcanoes in Hawaii. This minimises the twinkling or seeing, because the air is thinner. If you choose your location carefully you can also eliminate the of glare from street lights, which reflect off the atmosphere giving the sky an artificial brightness. The older sodium street lamps give the sky a sort of dirty orange glow. Air quality is important because any particles in the air will reflect light and make the sky glow. And finally weather. Ideally you would like to put your observatory above the clouds or at least some of them.
Taking all of that into consideration you have put your observatory in a remote place, away from cities and built up areas, 10 -15,000 feet above sea level.
Now the challenge is how you use the telescope. Very few astronomical observatories have an eyepiece attached to their telescopes and even fewer professional astronomers would look through an eyepiece to record measurements. Charge coupled devices or CCDs come into their own here. These are the devices which live inside all digital cameras that count light particles. Strap an industrial grade version of this on to the back of your telescope and you have a way of precisely counting the number of photons being transmitted from an astronomical source. By using filters with your CCD you can measure which colours appear brighter or slightly shifted to features with other colours, which combined with your knowledge of physics allows you, as an astronomer, to piece together what the object is and what processes happened to form it.
If you only have one telescope you are at the mercy of the elements, unless you can put it in the back of a van move it to and move it to a different Hawaiian island or remote mountain. For all practical purposes this is impossible. Many astronomers have frustrating observing runs where you travel to Hawaii, go surfing during the day in beautiful sunshine and then at night drive up the mountain to find that the clouds have rolled in so you can’t observe.
It sounds like that’s lots of fun but I can tell you that after 24 hours of travel the last thing you want to do is stay awake, up a desolate volcano, controlling a gigantic multimillion pound instrument in the freezing dead of night. The first night I went observing at the Caltech Submillimetre Observatory on Mauna Kea, my wife locked me in the observatory toilet. Which didn’t have heating. For an hour.
Fortunately we can avoid all of that hassle by making our telescope robotic. With carefully designed systems for monitoring weather, sky conditions, instrument statuses, telescope telemetry, a small amount of computer code and the internet, you can have yourself a robotic observatory. Many amateur astronomers have robotic observatories in their back gardens. We have one of the roof of the university physics department. But these are mostly dumb robots, that require a person at the other end who is remote controlling every aspect – like when to open the observatory dome, and what to observe. The key here is that the person with the remote control can be doing all of this from the comfort of their living room in their slippers with a mug of a cocoa, or even 4000 miles away in a more appropriate timezone for doing an observing run. I can tell you that your decision making process is so much better if you are working during your day time, without altitude sickness and not having endured 24 hours of air travel.
Another approach is to pay a telescope operator to sit up at the telescope every night and do your observing for you. This is how many professional observatories run. You have to feel sorry for sorry for these people because they live in some of the most beautiful, unspoiled places on Earth and they sleep most of the day because all night they are sitting at a computer observing for people they’ve never met. At the end of the night the download all the data on to a tape drive, DVD or if you are really lucky an online repository. You get your data at some unspecified date in the future. This can be really frustrating if you need the data urgently because you’ve just discovered something new and exciting. I can also be really embarrassing if you get your calculations wrong and ask for observations of a target which isn’t visible from that location, or to dim or you get the coordinates wrong. You wait a long time for useless data.
The really challenging part is then to remove the telescope operator and making the observatory totally autonomous. This requires much more computer code, which can make decisions about whether the sky conditions are good and what to observe from a pre-scheduled queue. You also have to build in contingencies for something going wrong. If the telescope gets stuck whilst slewing some part of the autonomous control system has to recognize the signs and make the observatory safe, and alert a person so that it can be repaired in 2,5,12 or 24 hours time.
Its a lot of hassle to make an observatory autonomous but it can make the difference between an ok observatory and world class one. If part of your software is an adaptive scheduler you can take all your observation requests and turn them into an efficiently packed together schedule with minimum amount of gaps or human made procrastination. You can increase your on-sky time, allows you to get more observations of more astronomical objects for more people. If you attach your observatory to an online repository, you can be observing and analysing your data within minutes of each other.
There is still the problem of you only having one telescope. What happens when the weather rolls in or worse still something happens to break your telescope. The answer is simple: build more telescopes and build them in different locations. Splitting your telescopes between the northern and southern hemispheres and spreading them out evenly across the globe is sensible because then you have full sky coverage. By doing this you now not only have a wet weather and technical difficulty contingency but you have something potentially more valuable. If you add in the internet and some more software, you have a telescope network, which is more powerful than the sum of its parts. Your intelligent autonomous scheduler has a much bigger resource to play with now, virtually guaranteeing that there will be somewhere on the globe suited to observe your important astronomical phenomena.
This sort of approach is being pioneered by Las Cumbres Observatory. Its a daunting task to build all of this from the ground up, all the software, electronics, and optics have been designed in house, but it is actually happening and telescopes are being deployed. This is the first example of an autonomous network of telescopes on this scale and is geared towards discovering and following-up transient phenomena which need to be rapidly observed or they are lost forever like exploding stars, chance alignment of distant planets orbiting distant stars and fast-moving asteroids and comets.
Over the past few years this is exactly the sort of thing I have been doing with Las Cumbres Observatory. Some of the most exciting results I have seen are because we have robotic telescopes which can rapidly respond to the first sighting of a new astronomical event. We have been involved in the discovery and classification of extrasolar planets by looking at a tiny dip in the brightness of a star which indicates a planet passing in front of us and the host star.
We have also been significantly involved in the follow-up measurements of newly discovered exploding stars, or supernovae. Having a good understand about how a supernova brightens and then dims, is crucial not only for understanding how these stars evolve but also because the peak brightness is used to measure how far away they are. We then use this to measure how far distant galaxies are away, and by combining that with other observations of these galaxies we can discover more about the history of the Universe and theorise about how it started based on what we observe. I told you astronomers had to be extra tricky every photon.
We have assisted in confirming 77 new Near Earth Objects (asteroids and comets passing very close to Earth) with follow-up observations, and discovered 21 of these objects serendipitously. These are particularly interesting because Near Earth Objects some of them cross Earth’s orbit. With robotic telescopes anyone can make exciting scientific discoveries from the comfort of their homes or even in the pub. We used to call these people ‘armchair astronomers’ but now they are part of a larger group of Citizen Scientists.
The capabilities of telescopes are continually evolving and will only get better with time. 400 years ago, with a telescope the size of a small dog, Galileo revolutionised the way we view the Universe. I wonder how different the Universe will seem in another 400 years.
This was written for the 2012 Pythagoras Lectures, aired in the Summer of 2012 on Radio Cardiff.