The Crowd and the Cosmos: Adventures in the Zooniverse
Page 1
The Crowd and The Cosmos
Praise for The Crowd and the Cosmos
‘ The Crowd and the Cosmos is a superbly written insight into the unique and powerful contribution enthusiasts from all walks
of life can make to scientific knowledge. It is also a fascinating
and much-needed description of how we acquire reliable
knowledge about Nature, from the search for planets and
perhaps civilisations around distant stars to observations of
Penguins in the Antarctic and what they can teach us about the
impact we are having on our own world.’
Brian Cox
‘Chris Lintott, is a modest genius. He has quietly revolutionised
modern Astronomy (and a few other branches of science) by
using digital platforms to involve the public in processing data.
Essentially anyone who wants to contribute some of their spare
time can, and is invited through Chris’s Zoooniverse projects to
do real science. Literally millions have taken up the invitation.
This is a beautifully readable book, which tells the story of the
Zooniverse and much more. Chris is delightfully anecdotal,
inclusive and witty, yet never shirks in-depth explanations of
the cutting edge science he’s delivering to us, almost before we
realise it! This is the New Age of Science for All!!!’
Brian May
‘ The Crowd and the Cosmos gives an authentic flavour of astronomical research and its appeal. But it's especially significant because it
offers a first-hand account of how Chris Lintott conceived and
led the “Zooniverse” project, thereby enabling huge numbers
to participate in significant research, and even make important
discoveries. His pioneering initiative has spawned similar
programmes in naval history, conservation, and other subjects—
triggering a benign social revolution in scholarship and education.’
Martin Rees
1
Great Clarendon Street, Oxford, ox2 6dp,
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© Chris Lintott 2019
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First Edition published in 2019
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CONTENTS
Preface
vii
1. How Science is Done
1
2. The Crowd and the Cosmos
39
3. No Such Thing as a New Idea
73
4. Into the Zooniverse
103
5. Too Many Penguins
135
6. From Supernovae to Zorillas
153
7. Serendipity
185
8. Is it Aliens?
207
9. Three Paths
227
References
249
List of Figure Credits
255
List of Plate Credits
257
Index
259
PREFACE
There is a faint star, dim and red, which shines feebly in the constellation of Aquarius. You would need a decent telescope
to see it at all, and in all of humanity’s history of studying the
Universe no one bothered giving it a name. The star, recorded in
catalogues as J23154776-1050590, is about 600 light years from
Earth; not too far on cosmic scales, but close enough that the
light we see now set off in the early fifteenth century, when King
Henry V’s English army was fighting the French at Agincourt.
Andrew Grey is a car mechanic who lives in Darwin, in north-
ern Australia. He’s also an amateur astronomer with a collection
of telescopes used for stargazing under the clear desert skies, and
in April 2016 he was the first person to realize that J23154776-
1050590 was a star worth keeping an eye on. Every so often, the
star does something odd. It winks, dimming slightly for an hour
or two.
These winks reveal the presence of something that would
otherwise be hidden. They’re caused by the regular passage of a
family of planets that happens to cross (or ‘transit’) the face of the star as seen from Earth. The effect is subtle—planets are small
compared to stars, and a single wink results in a dimming of
much less than 1 per cent of a star’s brightness—but we can see
them, and the immutable laws of physics dictate that as a planet
completes orbit after regular orbit around the star, that single dip
will be followed by another exactly one orbit later, and another
and then another, each adding to observers confidence that the
planet really exists.
Thanks to Andrew’s ability to notice these small changes in
brightness, we now know that J23154776-1050590 has at least five
viii prefaCe
Figure 1 Artist’s impression of five worlds around K2-138, discovered by citizen scientists in the Exoplanet Explorers project.
planets in its system. They crowd around the star, now given a
shorter catalogue number: K2-138 (Figure 1). Nor were these new
planets just another entry in the rapidly growing planet cata-
logue. Each is closer to their star than Mercury is to the Sun.
Packed in tightly, they form a resonant and harmonious pattern,
each world completing nearly exactly three orbits in the time
taken for the next one out to go around twice, an arrangement
which might persist for billions of years and which contains
within it secrets about these world’s formation.*
For centuries, and perhaps longer, astronomers dreamt of dis-
coveries like this. Yet finding new planets, and new solar systems,
&nb
sp; is now something that you can do at home. Andrew’s discovery
was made not with one of his telescopes, but with a web browser.
The star was one of many monitored by the Kepler space tele-
scope, launched and operated by NASA, whose team gave the
* While editing the book, we were able announce the discovery of a sixth planet which nearly fits the pattern, but is slightly off. Even more intriguing!
prefaCe ix
data it collected away for free. A team of astronomers at Caltech
had looked for likely planets, and shared their analysis online via
a website that allowed anyone to show up and help. A discovery
that twenty years ago would have put you in line for the most
prestigious prizes in science is now something that you, the
reader of this book, might manage in an otherwise idle lunch
hour.
Access to data from telescopes all over the world is now some-
thing that astronomers take for granted and, as it turns out that
being open with each other means that we’re also open to the
world, an increasing number of people are joining us in explor-
ing the Universe. Consider Despina, an obscure moon of Neptune
which was first discovered in images taken by the Voyager 2 space probe as it approached the ice giant in the summer of 1989. No
other probe has passed this way, and so we know very little about
Despina, other than the fact that it’s small, just 150 kilometres
across, and that it lives just inside one of the planet’s dark rings.
It is close enough to Neptune, in fact, that it is probably spiralling slowly inwards, compelled by the push and pull of tides induced
upon it by the planet’s gravity.
One day it may fall apart completely, but for now, there it sits.
Voyager 2 shot through the Neptunian system at high speed, and observations of the planet itself and the largest moon, Triton,
were the priority. Beyond noting its existence, little was done
with Despina in the short interval between discovery and fly-
past, and so all we have had for the last thirty years are a small set of images that make it look like a speckled jelly bean. Voyager’s encounter with Neptune was one of the things that made me, as
a schoolkid, avidly interested in space, but I can’t say that the
diminutive moon made much of a mark.
Despina is part of this story because of some amazing detective
work done by professional philosopher and amateur astronomer
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Ted Stryk. Since Voyager flew past, the best images of both Uranus and Neptune have come from the Hubble Space Telescope, and in 2006 Ted saw a Hubble image which showed one of Uranus’s larger moons, Ariel, transiting the disc. It’s a fun image, with both Ariel
and its shadow sharp against the pale green disc of the planet,
and Ted wondered if there were any similar shots from Voyager.
I would have bet good money on the idea that there was noth-
ing new to find in the Voyager dataset. Some missions produce enormous libraries of images, with plenty to keep scientists and
their friends going for decades. The Voyager probes, though, especially when in the outer reaches of the solar system, relied on a
fairly low bandwidth antenna to get data back to Earth, and so
relatively few pictures were ever sent. Each image from this
expensive, once-in-a-lifetime mission, had surely already been
extensively studied.
Ted, though, found something new. He got hold of the raw
data, and used modern technology and his expertise in image
processing to see something no one else had. In a sequence of
images taken over the course of nine minutes on 24 August 1989,
a small black dot can be seen on the planet’s blue, cloud-streaked
face. In one of the images, and only one, a small bright dot appears
near the edge of Neptune’s disc.
This, remarkably, is Despina, caught in transit during the
Neptune encounter as seen by the speeding Voyager probe
(Figure 2). The first dot, which appears in the whole sequence, is
the moon’s shadow, and the second dot the moon itself, just
entering the disc. It’s a beautiful and poetic set of images, a
moment in time captured during the only visit of a human-built
craft to the most distant planet in the Solar System—and it may
be useful too. Despina’s orbit isn’t well known, and pinning
down its presence in this particular set of images will help work
out how it behaves, and what its ultimate fate will be.
prefaCe xi
Figure 2 Despina, seen as a bright dot accompanied by its moving
shadow as seen by Voyager 2 and discovered by Ted Stryk. This is a mon-tage of four images, taken nine minutes apart.
Despina isn’t an isolated example. Planetary scientists on mis-
sions to the planets now regularly collaborate with a loose net-
work of image-processing experts to get the best out of their
data. When two Mars rovers, Spirit and Opportunity, landed on the red planet in 2004, the team behind them, led by Steve
Squyres and Jim Bell, made the decision to make the data their
robot explorers sent back available to the public as soon as it was
received by NASA. If you happened to refresh the web page at
just the right time, you could see an image taken on the surface
of Mars before anyone else on Earth.
The images have allowed scientists to show that what is now a
rusty desert was once a wet world. Mars, it’s now clear, once had
rivers and seas and lakes and oceans. The images from the rovers
have also fuelled the dreams and fired the imaginations of a com-
munity of fans back here on Earth, many of whom collaborated
xii prefaCe
to make use of the images sent back. This community had time
(and often, the skills) to do what the scientists could not, making
colour versions of images, charting their journeys on elaborate
maps, and creating mosaic views of landscapes and the odd rover
selfie. When the venerable magazine Aviation Week wanted to put Spirit on their cover, the image they used was created by four outsiders, who collaborated online without ever meeting. (One of
them, Doug Ellison, a graphic artist from Leicester, now works at
the Jet Propulsion Laboratory and was part of the team that oper-
ated the rovers.)
Whether it’s discovering new worlds or exploring Mars, the
web allows each of us to be part of the scientific enterprise. It’s
not just planets either. A distributed network of volunteers have
spent the last decade sorting through images of galaxies, and
mapping our own Milky Way. Others have helped conservation-
ists and scientists study and monitor animals, ranging from lions
in the Serengeti to coyotes in Chicago (and, lest you think this is
about exciting, charismatic species, they have also spent time
looking at many blurry images of kelp off the Californian coast
and watched videos of egg-laying intestinal worms). Old docu-
ments, from ancient Greek papyri to the records and letters of
anti-slavery campaigners in nineteenth-century America, have
been explored and transcribed by still more volunteers. Hundreds
of thousands of people have taken part in projects like this; in
this small corner of the world wide web, together they have con-
tributed to our u
nderstanding of the world and the cosmos.
I find it inspiring, and at a time when we tend to talk about the
internet and the communications revolution it has precipitated
in mostly negative terms, it’s a reassuring reminder that the vast
majority of people, both individually and collectively, are good.
Even when assembled as that most modern of bugbears—a
crowd on the internet—they are capable of remarkable feats of
prefaCe xiii
both generosity and skill. I hope reading this book will inspire
many people to rush to their nearest screen to try to find a planet
for themselves—data from NASA’s new planet hunter, the TESS
satellite, will be flowing in torrents by the time you read this
book—or, more simply, to take a more personal interest in the
Universe.
This book is the story of how I, a distractible astronomer,
ended up watching all of this activity unfold from a grandstand
seat. Each of the examples I’ve mentioned so far are from pro-
jects that live on a platform called the Zooniverse, built by a mer-
curial and talented team of web developers, scientists, and
educators which I’ve been proud to lead. I haven’t always had
space to stop and explain who did what, or how a million con-
versations led us collectively to solve the problems whose results
are presented here, but you should be aware as you read that
everything we’ve been able to achieve in the last few years is the
result of work by a team full of people much smarter than I.
It’s very easy to forget when describing a project such as the
Zooniverse that the technical approach taken is at least as
important as the science, and in this case everything we’ve done
has been shaped by early decisions to take both halves equally
seriously. That we did this was due to Arfon Smith, who was my
co-conspirator and the technical lead for the Zooniverse’s cru-
cial early years, and I would be remiss if I didn’t thank him here
for that insight and all the hard work. Among many others Lucy
Fortson and Laura Trouille in particular also deserve my grati-
tude and thanks for their leadership and support. The Galaxy
Zoo team—particularly Karen Masters and Bill Keel—have
taught me an enormous amount, and been very tolerant of my
distractions.