Stars in the city: an introduction to urban astrophotography

As a twelve year old astronomy nut, I was lucky enough to receive a small refracting telescope. Almost immediately, I utilised scrap timber to build an observatory in my back garden, just about large enough for two children (plus star charts, a moon map and at least as important in my opinion, a flask of hot chocolate). I recall it even had a sliding roof, thanks to a pair of dismantled wardrobe doors.

Although the imaging wasn't too bad - I lived in a small town, so light pollution was relatively low - I soon discovered that good optics are only part of the story: without a proper mount, a telescope can be next to useless. In this particular case, I obviously hadn't read the brief introduction to mounts in my trusty The Observer's Book of Astronomy by Patrick Moore. At any rate, I clearly didn't understand the difference between proper equatorial or alt-azimuth mounts and the piece of junk that allowed my refractor to sit on a table top. Therefore, except for getting to know the lunar landscape, I saw little that I couldn't more easily view with my 20x50 binoculars.

Jump forward thirty or so years and courtesy of a large tax refund I found myself in possession of a small reflector, complete with equatorial mount and right ascension motor. After some months getting to know it I started buying accessories, aiming to learn the ins and outs of astrophotography. Thanks to numerous websites I picked up some useful techniques and excellent free software - and as importantly, how to use the assemblage - and now feel it's about time I offered a one-stop-shop guide to getting the best images on a low budget in your own backyard. Of course there are plenty of books available, but most are at least one to two hundred pages long and often specify expensive kit, so this post is an attempt to cover the gap for those wanting an astrophotography 101 with the absolute minimum of basic equipment. Of course, it's entirely my approach, so there are no doubt plenty of other tutorials out there. But at least mine's short!

1. Equipment

I have to admit that I order all my kit from overseas, since New Zealand has few astronomy retailers and those there are appear to have a fairly limited range, often at uncompetitive prices. However, it is possible to accumulate a decent beginner's assortment for around a NZ$1000 / £500. I would always recommend a reflector as a first telescope, being far cheaper than a refractor with similar capability. The Newtonian is the most common, least expensive and easiest to maintain type of reflector, mine being a Sky-Watcher 130. As per the name, the primary mirror is 130mm (about five and a half inches in old money), which is really the minimum useful size for a reflector.

The telescope came with a red dot finder scope, several okay-ish eyepieces, a right ascension motor drive, a poor 2x Barlows and a reasonably stable equatorial mount. Since then I've bought a planetary camera, a good quality 2.5x Barlows, a compact camera adaptor, an adjustable polarising filter and a collimating eyepiece*. I've also made my own Bahtinov mask, courtesy of a website that supplies patterns for various diameter/focal length combinations. Although 'go-to' mounts are available, I agree with the general consensus that the best way to learn the night sky is by manually pointing the telescope, not just programming a target and letting the telescope slew into position for you.

*For complete newbies, a Barlows is a cheap method for increasing magnification with only a limited number of eyepieces, fitting into the eyepiece holder below the eyepiece. A collimator is used to check and correct misalignment between the primary and secondary mirrors, whilst a Bahtinov mask is a simple focussing aid.

I'm lucky to live in the 'winterless north' of New Zealand, but for those in colder climates it's probably wise to make or purchase a dew cap, or rather one for the main tube and another for the finder scope. A rubber eyecup for the eyepiece might also be a good idea; there's not much point in trying to observe anything if water is condensing on the mirrors or lenses.

I would recommend a CCD or CMOS telescope camera or modified webcam, since they are a lot cheaper than a digital SLR and far lighter. The EQ2 mount supplied with the Sky-Watcher needs adjusting on both axis depending on the combination of items in the eyepiece holder, otherwise at high angles it has a tendency to droop. The EQ2 counterweight can just about handle the long tube: experiments with a compact digital camera in a purpose-built mount have confirmed that additional off-centre mass requires regular fine-tuning to retain balance. Incidentally, I use a colour planetary camera since I tend to have short sessions - around two hours - and so only want to film each pass once rather than repeating in triplicate for colour filters, even if mono cameras achieve better resolution.

2. Where to observe?

Of course this is the least flexible part of astrophotography, since you are restricted by the buildings and trees in your garden - or any other convenient location. Not only is your view of the night sky limited by physical obstructions but pollution can severely impact viewing. As I have discussed previously, light pollution is the most obvious form, with street lighting often worse than that of buildings. I've found that even as low as ten percent cloud cover can degrade astrophotography, due to the artificial light reflecting off the clouds.

Heat pollution may be less obvious but can also severely reduce image quality. Therefore, try to avoid pointing the telescope directly above nearby rooftops or you will be looking through a rising column of hot air, either the radiating heat from earlier that day or leaking from poorly-insulated buildings that are heated at night. Also, never set the telescope up indoors and point it through an open window: the thermal variations will generate shimmering galore. Wind above the lightest of breezes cannot be recommended either, not just for 'scope instability but also because dust and particulates can deteriorate the viewing. High water vapour content is bad for the same reason; here in humid Auckland I'm frustrated by the hours before and after rain, meaning the best seeing I've ever had has been in high summer after a rain-free week.

Before using a reflecting telescope, it needs to be set up outdoors well in advance of the viewing session in order to allow the mirror to cool down to the ambient temperature. The cooling time is directly proportional to the primary mirror diameter, which for my 130mm is usually about one hour.

3. What to photograph?

For urban astrophotography I've found the moon and planets to be by far the best targets. By planets I mean just Mars, Jupiter and Saturn. Venus may be both large and bright but due to its cloud cover will never present anything other than a featureless crescent or globe.

The moon is endlessly fascinating, best observed between new moon and first or last quarter (i.e. half full). During these periods, the low-angle sunlight generates shadows that model the features without being overly bright. When observing closer to full moon I always use a polarising filter to reduce the incredibly intense light, but since sunlight is then perpendicular there is little modelling to give relief to the geology.

Jupiter is by far the best planetary target for small telescopes; in addition to the cloud patterns you can see some or all of its four largest moons (Ganymede, Callisto, Europa and Io), their number and position changing on a nightly basis. Saturn is an excellent target too, the angle of the rings varying widely. I've also found Mars to be surprisingly worthwhile even when not at its closest to Earth, with the major features clearly visible in reasonable seeing conditions.

The problem with deep sky objects in urban astronomy is that they are both difficult to locate and their light is easily degraded by light pollution and particulates. I've attempted to get images of more familiar DSOs such as the Orion Nebula with several cameras, but the results are hopeless.

Once you have some experience under your belt, you may want to attempt photographing the International Space Station. Various websites list details for near-future visible passes over any location, when it is easy to spot due to being obviously brighter than any other man-made orbiting object. However, since the ISS will only be visible for around four minutes each pass you have to quickly manoeuver the telescope whilst keeping it in an area that is only about thirty arc seconds in diameter. If I manage to get any image at all, it is usually a few dozen frames resembling an out of focus capital 'H', so it's definitely a target for those with a lot of patience - and good hand-eye co-ordination.

4. Locating targets

Although I'm against beginners using go-to mounts, there are various planetarium programs and mobile apps that are extremely convenient for locating target objects. I use Stellarium, excellent freeware that can be set to any location on Earth and has a night time (i.e. red on black) mode to help keep your eyes sensitive to the dark.

Northern Hemisphere observers are at an advantage compared to their counterparts south of the equator due to the ease with which the North Celestial Pole can be found. Not only is Sigma Octantis slightly further from the SCP than Polaris is from the NCP, it is considerably dimmer. Therefore I've always had great difficulty in lining up the telescope to the South Celestial Pole for setting circles with the polar axis motor drive. There are telescope-camera combinations that allow use of auto guiding software but I prefer the manual approach to finding your way around the night sky. Besides which, spotting the closer planets is pretty easy, the most common potential mix-up being Mars with the red star Antares (whose name after all means 'equal to Mars')! All in all, manually slewing the telescope using a printed or online star chart as a guide is the best way to learn.

5. Harvesting ancient light

I tend to take 20-60 seconds of video or still sequences when imaging the moon and planets, depending on various factors such as target brightness and seeing conditions. Planetary cameras allow some manual adjustments such as exposure length and gain, with shorter exposure lengths usually better so as to minimise degradation within a single image. When the seeing is reasonable I stack the planetary camera on top of the 2.5x Barlows, which gives a decent angular size for the planets. I've also used a compact CCD camera with an eyepiece and Barlows combination, but the camera adaptor is fiddly to align on three axis with the eyepiece and the extra weight can mean regular adjustments to the mount, depending on telescope angle.

6. Image processing

Once you have the raw video or sequence of stills there is a lot that can be done to improve the image quality, initially by aligning and stacking the best individual frames and discarding the rest. Again, there is a lot of freeware available to help with this. I use RegiStax, often creating 3 or 4 permutations from each sequence and then loading the best one in Photoshop for final tweaks. (If you cannot afford the latter, then GIMP - GNU Image Manipulation Program - is a great freeware alternative.) It can take a while to understand how to use the likes of RegiStax, but there are YouTube tutorials covering various processes and I always consider a trial and error approach to be a good way to learn!

So what sort of results can you expect from all this effort? The biggest factor in quality is undoubtedly the seeing conditions, which are outside of your control. However, just occasionally you get a perfect night. I find that it can take a few sessions to generate a half-decent image, so it definitely takes perseverance.  Since a picture is worth a thousand words, you can judge the results for yourself here.

Dung roaming: a controversial approach to cleaning up New Zealand's cattle waste

Although I've already discussed the dangers of using biological control in various countries, a couple of recent events suggested I should write an update that concentrates on one particular example in New Zealand. I've mentioned elsewhere that my local reserve in Auckland is home to a large number of non-native species, from Australian eucalyptus trees and the associated (but accidentally imported) Emperor Gum moth, to California quail and Mexican gambusia fish. But having seen rainbow skink in my local environs, including a neighbour's garden, I was surprised to learn last week they are not native but yet another unplanned Australian import. Sure enough, the 1947 classic Powell's Native Animals of New Zealand makes no mention of the species in the page on the indigenous common skink and copper skink.

Earlier this year I read Quinn Berentson's superb Moa: the life and death of New Zealand's legendary bird, which lists fifty-eight avian species as having become extinct since humans first arrived in the country less than a thousand years ago. And of course this decimation of native fauna and flora may not yet have ended, with NIWA for example fighting a rear guard action against unwanted marine incomers such as polychaete worms arriving on ship's hulls and in discharged ballast water. Various sources suggest that well over one hundred introduced species of land animals, birds and fish are now widespread in New Zealand: what chance does the native ecosystem stand against this onslaught?

To add insult to injury, I recently read an OECD chart delineating business spend on research and development as a percentage of GDP, and was shocked to find that New Zealand was fourth from bottom of twenty-six nations, coming below western Europe, South Korea, Japan, Australia, Canada and the USA. Are our captains of industry really so short-sighted? As a country that depends extremely heavily on its dairy industry - an industry that is currently in dire straits - it seems sensible to invest a large amount of R&D in this sector. But alongside the eco-friendly solutions such as minimising methane emissions, there has been a new programme of biological control aimed at one particular side effect of dairy farming, namely the enormous amounts of cattle dung produced.

Across the Tasman, Australia has already been working on a similar scheme for the past half century, deliberately introducing numerous species of non-native dung beetles. New Zealand, home to over ten million cattle in a 3:2 dairy-to-meat ratio, obviously has issues with bovine manure management. Due to the lack of native ruminants the country's fifteen indigenous dung beetle species have evolved to mostly inhabit forests rather than grazing land.

There are various reasons why speeding up the rate of dung decomposition would improve farm land and the landscape in general, from preventing mineral imbalance in the soil and contamination of waterways to reduction in animal-infesting parasites such as nematode worms. But is it worth the risk to the greater environment, considering the dismal track record of biological control schemes around the world?

The new project is not the first time such insects have arrived in the country: in addition to three species accidentally imported from Australia and South Africa from the late Nineteenth Century onwards, the Mexican dung beetle (Copris incertus) was deliberately introduced into three areas in the 1950s but only thrived in the warm Northland climate. It is the scale of the new research that has set it apart: following caged field trials, the past two years has seen the widespread introduction of eleven non-native species across seven regions on both North and South Islands.

Bodies such as the Institute of Environmental Science and Research (ESR) have investigated the potential dangers to human health and the local ecology, even testing if possums, carriers of bovine tuberculosis, might see the exotic insects as a new food source. Even so, some professional scientists have deemed it a biosecurity disaster and one can see their point: using data from other countries' programmes is hardly a fool-proof comparison, considering the profoundly different indigenous ecosystems of Australia and New Zealand.

As a child I heard about the food chain or pyramid, but this is something of a misnomer. Just as natural selection works with bushes rather than linear progression, so there are food webs consisting of a complex series of trophic interactions. Although exotic dung beetles are unlikely to displace their native counterparts due to lack of shared environments, it is possible that other native species of grassland-living insects could suffer, such as humble earthworms. The problem is that without testing in various regions over long periods of time, it isn't viable to rule out such side consequences. Yet it isn't possible to undertake such tests without release into the wild: do we have something of a catch-22?

Having said that, there are no obvious signs that Australia's long-established dung beetle programme has had anything like the deleterious effects of its other biological control schemes, such as the cane toad fiasco. But then fifty years is a very short time in ecological timeframes and what to the casual glance of a farmer appears to be equilibrium could be apocalyptic at dung beetle scale. I wish the project good luck, but cannot help feeling that having received far more than its fair share of obnoxious aliens, New Zealand is the last place that needs yet more exotic species introduced onto its green and pleasant land.

Sea monkeys: easy care pets or cheap lab animals?

As a former keeper of shield or tadpole shrimp (species Triops longicaudatus) in the UK, I miss the little blighters here in New Zealand, where they are banned as a biohazard. Although there is a rare native species, Lepidurus apus is apparently not suitable for keeping in household tanks; has anyone ever tried, I'd like to know?

Anyway, about four years ago I was looking for an alternative critter when I remembered someone at a party once mentioning sea monkeys, a hybrid species of brine shrimp suitable for keeping at home. Artemia nyos are very cheap to purchase and look after, with little in the way of paraphernalia required to keep them alive. (Incidentally, in addition to not being monkeys - obviously - they also don't live in the sea; the parent species are native to saline lakes.)

The most noticeable difference for me after Triops is that they don't require the frequent water changes that tadpole shrimp do. What's more they live somewhat longer: I've managed lifespans over six months, compared to just half that for Triops. In addition, sea monkeys can live in tiny tanks and so are the ultimate in pint-sized pets - or to be more accurate, three-quarters of a pint-sized pets.

Being only half the size of Triops, they require close-up observation; even with a themed tank, you are unlikely to get anything like a tropical aquarium experience. What's more, they refrain from digging motions and the other more interesting traits found in tadpole shrimp, mostly swimming on their backs, mating, or fanning through particles at the bottom of the tank for food. In fact, apart from some aquabatics, sea monkeys don't appear to have an awful lot to offer. For example, they don't have the range of behaviour that I've observed in individual tadpole shrimp, such as exuberant laps or hiding behind objects in the tank. Once you've observed them for a few months, the novelty begins to wear off, especially when they start dying in droves.

Therefore I thought that they might offer some interesting opportunities for scientific research with the minimum of apparatus. I initially tried a few changes - such as keeping a spotlight on at night during the first week of a new tank, partially for the warmth - but this was too informal to count as good research. I then started keeping a diary of the tanks, leading to a series of experiments aimed at finding the optimal conditions for maximising both number of individuals and longevity. I can't say that after three years' of research I have exactly found the brine shrimp equivalent of the elixir of youth but I've certainly enjoyed playing biologist, even if my methodology and laboratory conditions aren't quite up to professional standard (insert smiley here if you like).

Towards the end of the research period I explored some websites where other owners/breeders/keepers (delete as appropriate) had also experimented on the animals and their eggs. These raised some interesting questions, including concerns over the amoral nature of some practical science. Even so, it all gave me a good opportunity for to write this post!

For those without sea monkey experience, here's a brief summary of what is involved in their upkeep:

• A commercial water conditioner is added to a 12 ounce/350ml tank containing non-chlorinated (in my case, bottled) water, although the conditioner sachet often appears to include some eggs.
• A separate sachet of eggs is added a day or so later. The eggs usually hatch between two and five days after this, the water temperature directly correlating to the speed of hatching.
• Some days after hatching, the shrimp begin to be fed miniscule amounts of powdered algae, the frequency depending on the number of adults.
• The water level is topped up once every month or so with bottled water.
• Ideally, the tank is aerated every one or two days, in my case using an 'aqua leash' included with one of the tank kits.

So a fairly simple care regimen, then. None of my tanks have ever had more than seven adults at a time, which contrasts markedly with the congested tanks I've seen in internet videos. Whether it is the absence of light at night or cooler temperatures in general compared to other owners I'm not sure, but the lack of numbers was certainly not through a shortage of aeration or appropriate amounts of food, except during several months' of experiments as described in this summary of my research:

Q1: Could I raise sea monkeys using a ratio of water conditioner to water 30% lower than recommended?
A1: Negative. No eggs hatched. (See, I'm trying to use the correct scientific tone...)

Q2: Could I raise them using a tank substrate?
A2: Not wanting to waste eggs and conditioner I only performed this once, using finely crushed sea shells thoroughly rinsed in bottled water. No eggs hatched.

Q3: Did the brand of bottled water (with differing amounts of dissolved solids) make any difference to hatching numbers or longevity?
A3: Not noticeably.

Q4: Did a mature, mixed female-male population produce more hatchlings than a female-only population?
A4: Marginally, although after the initial hatching once a tank was set up, very few later nauplii survived more than a month.

Q5: Were, as I had read, the shrimp more photo-reactive when the tank was crossed by narrow beams of light in an otherwise dark environment?
A5: I saw very little evidence for this.

Q6: Did the distance from a window and direction/angle of daylight affect numbers?
A6: This was tricky, since around ninety minutes on a sunny window sill was all I allowed in order to prevent a tank transforming into a serving of Bisque du mer singe. But there was little evidence to suggest the amount of light altered the number or longevity of the population.

Q7: Did the tank temperature affect hatching numbers?
A7: I didn't want to use a normal tank thermometer, the tanks being so small, so I only had the fairly inaccurate sort that stick on the outside of aquaria. The only correlation I saw was that on colder nights it was better to keep tanks away from the window sill where it was obviously chillier than elsewhere in the room.

Q8: Did the frequency of aeration affect the population?
A8: I tried various permutations, from twice daily, to three times per week, to just once a week or even less, but this appeared to make little difference. Then again, I wasn't successful in raising more than five nauplii in any one 'mature' tank at a time, and so perhaps the population was too low to require greater oxygenation.

Q9: Did the feeding frequency affect the population?
A9: Again, I tried a range of schedules over several years, from once every five days to once per month. However, the low adult populations meant there was never any danger of starvation: their digestive tracts always looked full and at various times, individuals were accompanied by long strings of excrement. Hmm, nice!

Q10: Could I raise sea monkeys using a homemade water conditioner?
A10: This was the last experiment I undertook. I scoured the internet for the correct quantities of ingredients before trying several sea salt and baking soda ratios, but no eggs hatched after a month.

After I had completed these experiments, I searched the internet and found that my methods were rather tame compared to some of the research conducted on sea monkeys, and indeed brine shrimp species in general. Therefore here are some other potential experiments for those with the inclination:

1. Try other foods, such as baker's yeast
2. Try rain water or using self-created distilled water
3. Conduct water quality tests (aquarium kits such as for the ammonia/nitrate/nitrite cycle)
4. Egg hardiness, such as freezing and microwaving before attempting to hatch them*
5. Different oxygenation techniques, such as blowing (not exhaling) a fresh intake of air through a straw.

*I'm too squeamish for this sort of thing. Does it make me a poor amateur biologist? After all, it's not as if I'm looking to cure diseases or any other really useful addition to humanity's knowledge; it's just some interesting minutiae on small invertebrates. Not worth putting them through it, really!

Although they are claimed to be easy to raise - indeed, other species are used for toxicity testing and their eggs subjected to cosmic ray experiments - I don't seem to have had much luck with breeding large populations (or in a rather more scientific tone, the condition of my tanks has proved to be sub-optimal). When one adult died, most of the other adults usually followed within a week. Despite frequent matings, lasting hours or even days and repeated several times per week, I've never seen more than five nauplii hatch in the same week in a mature tank. In addition, most seem to die after the first few instars, with very few reaching maturity. On the other hand, I once saw a tank with fully-grown shrimp belonging to a child who had added food daily but never aerated. Despite the water being obscured by thick algal growths, a few individuals managed to hang on in a presumably very oxygen-poor environment. Yet my zealous attention has seemingly had little impact!

So whilst they don't live up to the cuddliness of say guinea pigs, they are extremely useful as err...experimental guinea pigs, as it were, for the amateur biologist. And yes, watching the aquabatics can be fun, too!

Presenting the universe: 3 landmark science documentary series

They say you carry tastes from your formative years with you for the rest of your life, so perhaps this explains why there are three science documentary television series that still have the power to enchant some decades after first viewing. Whilst there has been no shortage of good television science programming since - Planet Earth and the Walking with... series amongst them - there are three that remain the standard by which I judge all others:

1. The Ascent of Man (1972) - an account of how humanity has evolved culturally and technology via biological and man-made tools. Presented by mathematician and renaissance man Jacob Bronowski.
2. Cosmos (1980) - the history of astronomy and planetary exploration, interwoven with the origins of life. Presented by Carl Sagan (as if you didn't know).
3. The Day the Universe Changed (1985) - a study of how scientific and technological breakthroughs in Western society generate paradigm shifts. Presented by the historian of science James Burke.

All three series have been proclaimed 'landmark' shows so it is interesting to compare their themes, viewpoints and production techniques, discovering just how similar they are in many ways. For a start, their excellent production values allowed for a wide range of international locations and historical recreations. They each have a charismatic presenter who admits to espousing a personal viewpoint, although it's quite easy to note that they get progressively more casual: if Jacob Bronowski has the appearance of a warm elder statesman then Carl Sagan is the father figure for a subsequent generation of scientists; James Burke's on-screen persona is more akin to the cheeky uncle, with a regular supply of puns, some good, some less so.

To some extent it is easy to see that the earliest series begat the second that in turn influenced the third. In fact, there is a direct link in that Carl Sagan hired several of the producers from The Ascent of Man for his own series, clearly seeing the earlier show as a template for Cosmos. What all three have is something extremely rare in other science documentaries: a passion for the arts that promotes a holistic interpretation of humanity's development; science does not exist in isolation. As such, the programmes are supported by superbly-illustrated tie-in books that extend the broadcast material from the latter two series whilst Bronowski's book is primarily a transcript of his semi-improvised monologue.

In addition to considering some of the standard examples of key developments in Western civilisation such as Ancient Greece and Galileo, the series include the occasional examination of Eastern cultures. The programmes also contain discussions of religions, both West and East. In fact, between them the series cover a vast amount of what has made the world the way it is. So not small potatoes, then!

The series themselves:

The Ascent of Man

To some extent, Jacob Bronowski was inspired by the earlier series Civilisation, which examined the history of Western arts. Both series were commissioned by David Attenborough, himself a natural sciences graduate who went on to present ground-breaking series in his own discipline as well as commissioning these landmark programmes. (As an aside, if there are any presenters around today who appears to embody the antithesis of C.P. Snow's 'the two cultures' then Sir David is surely in the top ten).

Bronowski's presentation is an astonishingly erudite (for all its improvisation) analysis of the development of our species and its technological society. Although primarily focused on the West, there is some consideration of other regions, from the advanced steel-making technology of medieval Japan to Meso-American astronomy or the relatively static culture of Easter Island. Time and again, the narrative predates the encumbrance of political correctness: that it was the West that almost solely generated our modern technological society - the 'rage for knowledge' for once outshining dogma and inertia.

Of course, it would be interesting to see how Bronowski might have written it today, in light of Jared Diamond's ground-breaking (in my humble opinion) Guns, Germs and Steel. Although he works hard to present science, the plastic arts, literature and myth as emerging from the same basic elements of our nature, it is clear that Bronowski considers the former to be much rarer - and therefore the more precious - discipline. Having said that, Bronowski makes a large number of Biblical references, primarily from the Old Testament. In light of the current issues with fundamentalism in the USA and elsewhere, it is doubtful that any science documentary today would so easily incorporate the breadth of religious allusions.

If there is a thesis underlying the series it is that considering how natural selection has provided humanity with a unique combination of mental gifts, we should use them to exploit the opportunities thus presented. By having foresight and imagination, our species is the only one capable of great heights - and, as he makes no pretence of - terrible depths. As he considers the latter, Bronowski admits that we should remain humble as to the state of contemporary knowledge and technology, which five hundred years hence will no doubt appear childlike. In addition, he states that belief in absolute knowledge can lead to arrogance; if we aspire to be gods, it can only end in the likes of Auschwitz. But his final speeches contain the wonderful notion that the path to annihilation can be avoided if science is communicated to all of society with the same vigour and zest as given to the humanities.

Cosmos

I was already an astronomy and astronautics fan when I saw this series. Its first UK broadcast slot was somewhat later than my usual bedtime, so it seemed a treat to be allowed to stay up after the rest of the family had gone to bed. Like Star Wars a few years before, it appeared to me to be an audio-visual tour-de-force; not surprisingly, both the tie-in hardback and soundtrack album arrived on my birthday that year.

Nostalgia aside, another key reason for the series' success was the charisma of the presenter himself. Much has been written of Sagan's abilities as a self-publicist, and the programmes do suffer from rather too many staring-beatifically-into-the-distance shots (as to some extent replicated more recently by Brian Cox in his various Wonders Of... series). Of course, it must have taken considerable effort to get the series made in the first place, especially in gaining a budget of over $6 million. After all, another great science populariser, the evolutionary biologist Stephen Jay Gould, never managed to gain anything beyond the occasional one-off documentary.

What is most apparent is Sagan's deep commitment to presenting science to the widest possible audience without distorting the material through over-simplification. However, in retrospect it is also obvious that he was using ideas from several scientific disciplines, such as the Miller-Urey experiment, to bolster his opinions on the likelihood of extra-terrestrial life. To some extent his co-writers reined him in, the final episode given over not to SETI but to plea for environmental stewardship.

Whilst the series is primarily concerned with a global history of astronomy and astrophysics, supplemented with first-hand accounts of planetary exploration, Sagan like Bronowski is equally at home with other scientific disciplines. He discusses the evolution of intelligence and incorporates elements of the humanities with equal aplomb. Another key element is the discussion of the role superstition and dead ends have played in the hindrance or even advancement of scientific progress, from Pythagorean mysticism, via Kepler's conflation of planetary orbits with the five Platonic solids, to Percival Lowell's imaginary Martian canals. Although Sagan repeats his earlier debunking of astrology, UFO sightings and the like, he doesn't rule out the role of emotions in the advancement of science and technology, citing for example the rocket pioneer Robert Goddard's Mars-centred epiphany.

Perhaps the primary reason that the series - despite the obvious dating of some of the knowledge - is still so engaging and why Sagan's narration is so widely quoted, is that he was a prose poet par excellence. Even when discussing purely scientific issues, his tone was such that the information could be effortlessly absorbed whilst allowing the viewer to retain a sense of wonder. Of course, Sagan had ample assistance from his two co-writers Ann Druyan and Steven Soter, as clearly proven by their scripts for the Neil deGrasse Tyson-hosted remake Cosmos: A Spacetime Odyssey. Nonetheless, it is hard to think of another presenter who could have made the original series the success it was on so many levels.

The Day the Universe Changed

Although James Burke had already made a large-scale history of science and technology series called Connections in 1978, it contained a rather different take on some of the same material. By focussing on interactive webs, the earlier series was somewhat glib, in that some of the connections could probably be replaced by equally valid alternatives.

In contrast, The Day the Universe Changed uses a more conventional approach that clearly shares some of the same perspectives as the earlier programmes. Like The Ascent of Man and the Cosmos remake, mediaeval Islamic science is praised for its inquisitiveness as well as the preservation of Classical knowledge. Burke was clearly influenced by his predecessors, even subtitling the series 'A Personal View by James Burke'. Perhaps inevitably he covers some of the same material too, although it would be difficult to create a brief history without reference to Newton or Ancient Greece.

As with Bronowski, Burke integrates scientific advances within wider society, a notable example being the rediscovery of perspective and its profound effect on contemporary art. He also supports the notion that rather than a gradual series of changes, paradigm shifts are fundamental to major scientific breakthroughs. In effect, he claims that new versions of the truth - as understood by a scientific consensus - may rely on abandonment of previous theories due to their irreconcilable differences. Having recently read Rachel Carson's 1950 The Sea Around Us I can offer some agreement: although Carson's geophysical analysis quietly screams in favour of plate tectonics, the contemporary lack of evidence lead her to state the no doubt establishment mantra of the period concerning static land masses.

What Burke constantly emphasises even more than his predecessors is that time and place has a fundamental influence on the scientific enquiry of each period. Being immersed in the preconceived notions of their culture, scientists can find it as difficult as anyone else to gain an objective attitude. In actuality, it is all but impossible, leading to such farcical dead-ends as Piltdown Man, a hoax that lasted for decades because it fulfilled the jingoistic expectations of British scientists. Burke's definition of genius is someone who can escape the givens of their background and thus achieve mental insights that no amount of methodical plodding can equal. Well, perhaps, on occasion.

The series also goes further than its predecessors in defining religion as anti-scientific on two grounds: its demand for absolute obedience in the face of logic and evidence, with reference to Galileo; or the lack of interest in progress, as with the cyclical yet static Buddhist view, content for the universe to endlessly repeat itself. Burke also shows how scientific ideas can be perverted for political ends, as with social Darwinism. But then he goes on to note that as the world gets ever more complex, and changes at an ever faster rate, non-specialists are unable to test new theories in any degree and so are having to rely on authority just as much as before the Enlightenment. How ironic!

All in all, these common threads are to my mind among the most important elements of the three series:

1. Science and the humanities rely on the same basic processes of the human brain and so are not all that different;
2. Scientific thinking can be as creative an endeavour as the arts;
3. Scientists don't live in a cultural vacuum but are part and parcel of their world and time;
4. Religion is the most change-resistant of human activities and therefore rarely appears sympathetic to science's aims and goals.

As Carl Sagan put it, "we make our world significant by the courage of our questions and the depth of our answers." For me, these three series are significant for their appraisal of some of those courageous explorers who have given us the knowledge and tools we call science.