The Crowd and the Cosmos: Adventures in the Zooniverse

by Lintott, Chris

star cluster. There were maybe twenty or so stars, of roughly

  equal brightness, with hints at the edge of visibility that many

  more existed. Surprised I’d never heard of such a glorious cluster

  close to a tourist stop as popular as the Orion Nebula, I looked it

  up in my star atlas and found, where the cluster should be, noth-

  ing but a blank space. In those days before the internet was avail-

  able at home at the flick of a screen there was no way for me to

  immediately investigate further, and I proudly picked up a pencil

  (not a pen—I obviously wasn’t quite that confident!) and marked

  its position very carefully on the atlas, next to a carefully calli-

  graphed label: ‘Lintott 1’.

  I went to bed that night not really believing that I’d made a dis-

  covery, but I couldn’t stop a tiny part of my brain thinking that

  there was at least a chance that I might have done. Of course,

  when I made it to the internet* the next day the cluster turned

  out to be well known. Its true name, NGC 1981, doesn’t have the

  sonorous ring of Lintott 1, but has the advantage of having been

  in use by astronomers since the late nineteenth century (Plate 1).

  Minor though it was, the incident stuck with me as my closest

  contact with a long-ago epoch when anyone with time, luck, and

  modest equipment could make a discovery. The astronomical

  books and magazines I immersed myself in were full of tales of

  amateurs discovering enormous storms on Saturn, spectacular

  comets, or the twinkling of variable stars, but they did so partly

  because they had kit beyond my wildest dreams. People like

  * People younger than me may be surprised by the idea that the internet wasn’t immediately available from home. It was a bleak time.

  8 How Science iS Done

  retired telecoms engineer Tom Boles of Suffolk brought enor-

  mous dedication to their searches, in Tom’s case resulting in the

  discovery of more than a hundred supernovae (explosions that

  mark the death of massive stars), but they also depended on tens

  of thousands of pounds’ worth of automated telescopic power.

  These super-amateurs were making spectacular progress, but

  they were doing so by effectively professionalizing their astron-

  omy, often spending a fortune on advanced kit. The market

  for buckets and spades being unlikely to expand to a sufficient

  extent, I felt that finding even something as quotidian as an

  undiscovered asteroid—once so commonplace as to have

  attracted the reputation of celestial vermin—would be forever

  beyond my reach. My romantic vision of amateur astronomy

  with a small telescope dead, I moved on to become a professional

  astronomer.*

  Here, as with the amateurs, I found a community and a way of

  life that was under severe assault from the onrushing forces of

  technological advance. While once individual universities or

  particular countries aspired to have their own research-grade

  telescope, a severe epidemic of ‘aperture fever’—the desire for

  larger and larger telescopes—has hit the astronomers of the

  world, leaving us with no option but to pool resources in ever

  larger and more expensive facilities. For most of the twentieth

  century, the world’s largest working optical telescope was the

  200-inch Hale Telescope at Mount Palomar in California. Built

  * That’s not to say that there isn’t anything worth doing with a small telescope. I’ve had hours of pleasure staring at the Moon, Jupiter, the Orion Nebula, and countless other objects. If you’ve never looked through a telescope, find your nearest astronomical society right now, go along to a public observing night, and get them to show you the sights. It’s more than worth it, even if you don’t get a comet named after you. There really is something special about having photons from far away objects hit your retina, something which just can’t be replicated by looking at even the most impressive photos.

  How Science iS Done 9

  during the 1930s and then commissioned in the immediate after-

  math of the Second World War, the 200” is a beautiful relic of a

  bygone age, to the extent that the original design’s reliance on a

  newfangled technology—welding—was considered risky when

  it was completed. The welding worked, and the telescope was

  unrivalled until the 1990s.*

  Since then, a host of telescopes with mirrors eight metres

  (307 inches) or more across have been made, and astronomers

  are working on three separate projects that take us up to the

  equivalent light-collecting area of a mirror thirty metres or

  more across. One of the projects, now known logically enough

  as the European Extremely Large Telescope (EELT), started life

  as a concept called OWL—the OverWhelmingly Large Telescope.

  That was supposed to sport a mirror one hundred metres across,

  and it’s been suggested they could have kept the acronym but

  have it stand for Originally Was Larger. The EELT will still be a

  monster. Its dome, for example, is the size of a sports stadium,

  but competition to use such an enormous facility when it’s

  completed in the mid-2020s will be intense. With fewer large

  facilities available in each generation to be shared among the

  growing community of astronomers, the pressure to make the

  best use of every second of observing time has grown, and that’s

  had serious consequences.

  My PhD work involved several trips all the way from University

  College London in the heart of Bloomsbury to the Big Island of

  * A larger telescope was built by the Soviet Union in the mid-1970s, but it was plagued by problems bad enough for most to discount it in the competition for the world title. The original mirror was so bad it had eventually to be replaced, but even then the telescope remained almost neurotically sensitive to changes in temperature. That being said, with a lot of help from those who know it well, my collaborators and I have managed to get good data from it, so perhaps writing it out of the history books is a tad unfair.

  10 How Science iS Done

  Figure 3 The summit of Mauna Kea in Hawai’i, home to some of the best conditions for astronomical observing anywhere in the world.

  Hawai’i, with the aim of taking advantage of the crystal clear

  skies available to observatories on top of the (hopefully) dor-

  mant Mauna Kea volcano (Figure 3). It is a spectacular and other-

  worldly place, an hour or two’s drive from palm-lined beaches

  yet regularly covered in snow. It is, in fact, the summit of the

  world’s tallest mountain, double the height of Everest when

  measured from its summit more than 10,000 metres above sea

  level to its base deep in the ocean, and high enough that the

  low air pressure at the top presents a serious obstacle to clear

  thinking—an environment so hostile that the only thing that

  lives on the summit is a species of beetle found nowhere else on

  Earth. I’ve always wanted to see a Wēkiu bug, as they’re known—

  a strange creature which sits and waits for food in the form of

  smaller insects to be blown up to it by the winds that sometimes

  sweep across the summit, and is surely evolving to consume

  astronomers—but they are very rare.

  Mauna Kea must be a strange place to spend most of you
r days.

  I wasn’t too surprised to discover that several of the staff had been

  How Science iS Done 11

  submariners in their previous life, and were therefore presumably

  acclimatized to spending lots of time shut into metal boxes in a

  dark and hostile environment.

  Whatever it’s like to spend a significant proportion of your

  time there, it was a glorious place to visit, and I loved leaving the observatory buildings for a glimpse of a Mars-red dusty landscape high above bright blue sea or, better, for a spectacular

  night sky illuminated only by the stars and, just occasionally

  and far below, the flickering that marks the flow of magma from

  the still-active Kı̄lauea volcano into the ocean. (Astronomers

  have had a slightly more exciting time with Kı̄lauea recently, as

  the major eruption in the summer of 2018 produced a cone of

  sparks that could be seen from the summit as well as producing

  warnings of shut airspace and toxic vog, a volcanic fog, across

  the island. I know at least one survey that’s six months behind

  because of delay caused by fear of volcano-induced earth-

  quakes.)

  The dream of travelling to this amazing place, and being there

  on a scientific mission with purpose, was a large part of what

  attracted me to being an astronomer, but things are changing

  rapidly. To gain access to the telescope that I used in Hawai’i, one

  bids for access, competing against other astronomers to explain

  the (scientific) justification for being allowed to take the controls.

  This can be tricky, requiring one simultaneously to argue that

  the results will be transformative, and that you know what they

  will be sufficiently well that you can promise the time won’t be

  wasted.

  Still, if successful then the telescope was yours for the night

  and all you needed was a bit of luck and a clear sky. If conditions

  were lousy (and too much time spent under beautiful Hawai’ian

  skies tends to lead to over-optimistic planning or some very

  picky observers who want nothing but the calmest, stillest

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  nights) then there is nothing for it but to turn round and apply

  again. Desperation, not to say depression, could set in; I remem-

  ber observing with a radio telescope while rain swept across the

  mountain top, washing away any chance of decent data, and on

  another occasion nearly a week spent kicking pebbles along the

  gloriously palm-swept beach in high dudgeon at the sheer unfair-

  ness of cloud.

  Worse from the observatory’s point of view are the nights

  where I got lucky, or at least luckier than I should have. My PhD

  was mostly on the subject of astrochemistry, and I’d got time to

  go looking for molecules in space using a dish fifteen metres

  across known as the James Clark Maxwell Telescope, or JCMT.

  The JCMT works in the region of the spectrum that astronomers

  call the ‘sub-mm’ which and everyone else calls microwaves,

  which explains why it was high on the summit of a volcano. Your

  microwave oven works by firing waves at a wavelength chosen to

  excite the water in your food; the water in the atmosphere emits

  radiation at similar wavelengths, so from ground level the micro-

  wave sky shines brightly. By climbing a mountain we could get

  above most of the atmosphere’s water and see clearly out into the

  cosmos.

  I was searching for chemicals like hydrogen cyanide in and

  among the clouds of star-forming regions like the Orion Nebula.

  That isn’t quite as quixotic a quest as it sounds—the surfaces of

  dust grains in star-forming nebulae provide excellent sites for the

  sort of chemistry that forms complex molecules, and observing

  them provides more information than physical measurements

  alone ever could—but because for the most part we were happy

  with a single detection, rather than needing a map, a blurry view

  would do and these observations could be completed when con-

  ditions weren’t great. Nights with the best ‘seeing’—those when

  the air is crisp and still—would be better spent on high- resolution

  How Science iS Done 13

  mapping or imaging projects, but if one of those came along

  when I was on the telescope then it was going to be used for

  detecting hydrogen cyanide no matter how good the skies

  became.

  When both the astronomer sitting miserably on the beach and

  the observatory management started wondering how to make

  their multimillion dollar instruments more productive, it was

  only a matter of time before we found our way to a more efficient

  means of doing things. Gradually, over the past twenty years, the

  major observatories have shifted their operations to a model in

  which observations are dynamically scheduled; if the conditions

  improve, then high-priority objects which require the best wea-

  ther can be targeted and previously scheduled work shelved tem-

  porarily. In most cases, it’s become rare to travel to a telescope,

  and rather than carrying back precious images in triumph from

  Hawai’i, or Chile, or the Canary Islands, the arrival of fresh data

  is signified by the ping of an email hitting my inbox. I miss my

  observing trips, but I worry more about the next generation of

  students who won’t necessarily have any hands-on experience

  with where their data come from.

  A healthy respect for data is critical in developing scientific

  scepticism, but once the astronomer was removed from the pro-

  cess of observing it at least became clear that new ways of work-

  ing were possible. Whereas astronomers like me are used to

  observatories, general purpose facilities that are built for a multi-

  tude of tasks, what we’re getting increasingly in astronomy are

  experiments; there’s a tendency to move away from targeted

  observations altogether and towards collaborative surveys of

  large chunks of sky. Such surveys produce ever-larger reposito-

  ries of data held in trust for hundreds or even thousands of scien-

  tists to use, none of whom need have gone anywhere near the

  telescope upon which their research depends.

  14 How Science iS Done

  The most successful by far of these projects is called the Sloan

  Digital Sky Survey. It’s named for and funded by the foundation

  set up in the memory of Alfred P. Sloan, the man whose modern

  and, above all, efficient management techniques turned General

  Motors into the colossus that bestrode mid-twentieth-century

  America. He would have approved, I suspect, of the business-like

  way that his namesake fulfilled its primary mission, scanning the

  sky from its home in New Mexico in order to create a three-

  dimensional map of the Universe including nearly a million

  nearby galaxies (Figure 4).

  Is a million galaxies a lot? A single, medium-sized galaxy like

  our own Milky Way contains roughly one hundred billion stars,

  and so Sloan’s sample contains plenty of interest. Yet there are at

  Figure 4 The Sloan Digital Sky Survey telescope in New Mexico. The

  main mirror is 2.4 met
res across.

  How Science iS Done 15

  least one hundred billion galaxies or so within the span of the

  observable Universe—as many galaxies, in fact, as there are stars

  in the Milky Way—and so this, the most detailed map we have of

  our surroundings, only includes 0.001 per cent of the available

  sample (Plate 2). Even by the standards of Earth’s medieval map-

  makers, that’s a lot of undiscovered country marked ‘Here be

  dragons’.

  Yet the effort isn’t hopeless, and another analogy might help.

  Election pollsters in the US are faced with predicting the behav-

  iour of something like a hundred million people, yet typically

  use a sample of maybe a few thousand voters who they can reach

  on the phone or online. The ratio between observed and esti-

  mated samples is almost the same, and so we might conclude

  that we should expect our knowledge about the Universe based

  on the Sloan observations to be about as accurate as a single

  opinion poll. Actually, things aren’t that bad. Not only are galax-

  ies much simpler than people (a fundamental truth that makes

  astrophysics possible), but the Universe is much less variable on

  large scales than is opinion in America. For most purposes,

  therefore, we can assume that the volume covered by Sloan is a

  typical chunk of the Universe, and draw conclusions about the

  whole based on what the survey shows us.

  One can, of course try and look deeper into the Universe as

  well. One of the great advantages astronomers have in trying to

  understand the Universe is our ability to see into the past. Sloan

  is a survey of the local and thus the present-day Universe, but as

  we look further away we receive light which has taken billions of

  years to reach us. By combining our views of near and far we can

  piece together the whole story.

  The main scientific goal for which Sloan was built was to study

  the carefully plotted positions of its million galaxies in order to

  measure the expansion of the Universe. The galaxies are, in this

  16 How Science iS Done

  kind of study, nothing but trace particles, carried along on the

  grand expansion of space like so much flotsam carried by a river

  in flood. The first step towards this grander goal, though, was to

  identify enough galaxies, and that meant imaging a large area of