In June, 2007, the Nobel Foundation sponsored a special symposium in Stockholm, inviting top researchers to discuss the physics of "exoplanets" - planets that orbit stars other than the sun.

The quest for far-off worlds, once dismissed as sheer fantasy, is now considered the "other space race." Such planets may help humanity realize its ancient dream of finding extraterrestrial life, and finding the very first of them has gone down as one of the great accomplishments of 20th-century astrophysics.

In fact, the gathering in Sweden was a nudge-nudge, wink-wink indication from the secretive Nobel gatekeepers that the reward for this discovery will be a prize in physics. Perhaps the one that is to be announced in 10 days. This is, after all, the International Year of Astronomy.

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If the award seems certain, who will receive it is anything but. Will it go to the American or European astronomers credited with making with the initial discoveries? Just last week Swiss researchers revealed that they have found the first new planet that is, like Earth, terra firma, rather than an amalgam of gases akin to Jupiter.

Or will the Nobel committee members keep in mind the vagaries of scientific endeavour and award the prize, at least in part, to two dark horses in this race?

"Gordon Walker and Bruce Campbell were the real true pioneers," says Alan Boss, an astrophysicist at the Carnegie Institution in Washington, D.C., and author of a new book called The Crowded Universe: The Search for Living Planets .

He is referring to the British Columbia-based astronomers who pioneered the world's most successful search technique for exoplanets, and published the first scientific paper that accurately reported the detection of one. Unknown to most Canadians, theirs is a compelling a tale of innovation and determination - but one that fell short.

After laying their claim to having discovered the first exoplant, Prof. Walker, in an attack of scientific self-doubt, retracted it. By that point, his colleague had already quit astronomy in frustration.

As a result, their enormous promise ended in heartbreak - a classic example of the physical and psychological challenges of the scientific journey.

TWO CANADIAN S 'INVENTED THE TECHNIQUE WE STOLE'

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Mr. Boss is not alone in acknowledging the Canadians' achievement.

Geoff Marcy, a University of California at Berkeley astronomer and the world's leading exoplanet hunter, has helped to find 170 of the approximately 360 exoplanets discovered so far. And he says the Canadians "invented the technique that we stole … if it wasn't for Bruce Campbell, you wouldn't be talking to me."

He says this over the phone from Berkeley while remotely monitoring results from the giant 10-metre Keck Telescope atop Mauna Kea, a dormant volcano in Hawaii, in a bid to verify sightings of new planets being made by NASA's Kepler space telescope.

Kepler, launched in March, is the first telescope powerful enough to spot planets as small as Earth revolving around distant stars. In mid-August, the Kepler team announced that the telescope is working perfectly and is on target to reach its ambitious goal: a census of such planets by 2012. To do this, it is watching about 100,000 stars in the Milky Way for "transits" - the period when planets pass in front of their stars, causing mini-eclipses that temporarily dim the stars' light.

"Kepler will not find E.T. - it's hoping to find E.T.'s home," Bill Borucki, the NASA visionary leading the mission, said when the telescope was launched.

"Whether we show that there are lots of Earth-like planets, or very, very few, we'll answer a question that has been asked by mankind for millennia: Are there other worlds, or are we alone?"

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The excitement over the search for alien worlds belies a huge shift in our view of the cosmos. While by 1980 moviegoers were accustomed to a Star Wars menagerie of fictional worlds, astronomers counted only nine real planets: those of our solar system.

"It is quite hard nowadays to realize the atmosphere of skepticism and indifference in the 1980s to proposed searches for exoplanets," Prof. Walker writes in a recent article.

The skepticism was fuelled by almost a half-century of false alarms, often caused by the fact the planets are hidden in the glare of their stars.

One was reported in 1967 in orbit around Barnard's Star and made it into astronomy textbooks, only to fade ingloriously in 1973 when it was shown to be not a planet, but a problem with a telescope.

In another case, a venerable U.S. astronomer arrived at what was to be the announcement of an alien world he'd found, only to admit that he'd actually made a mathematical error. (He was hailed nonetheless for being brave enough to break the news himself.)

"There was literally a gravesite with lots of tombstones of planets that had come to life erroneously and then laid to rest," says Prof. Marcy.

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If other worlds were out there, astronomers knew they were devilishly hard, maybe impossible, to detect. Into this astronomical minefield walked the two Canadians.

They met 40 years ago this month, when Bruce Campbell, a 21-year-old third-year student in engineering and physics at the University of British Columbia, took his first astronomy class. At the front of the lecture hall was Gordon Walker, a 33-year-old, Cambridge-trained Scottish immigrant just starting out as a professor.

Weeks earlier, Neil Armstrong had taken humanity's first step on another world, and the cosmos suddenly seemed more accessible, but Prof. Walker and Mr. Campbell didn't set out to launch the first dedicated search for alien worlds. They were astronomy tech geeks (Mr. Campbell scored top marks in the Walker class, called "astronomical measurements") drawn together by a fascination with building better, faster telescopic equipment.

'WE COULD START LOOKING FOR PLANETS'

In astronomy, the better you see, the more you see. Just as Galileo's radical insights 400 years ago were based on a new telescope with greater acuity, the two knew they were on to something when they made a major leap in the ability to tease apart starlight.

"I heard myself say, 'We could start looking for planets,'" says Prof. Walker, now 73 and still very active in astronomy as an adjunct professor at the University of Victoria.

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"I don't know where the idea came from. That's how these things happen in science: Suddenly a light turns on. It's the art of the possible."

What they had developed was an amazingly more accurate way of clocking a star's movement. We think of stars as fixed points of light in the night sky, when in fact they move, a lot. Their thermonuclear nature makes them expand and contract. Also, they rotate just as Earth does on its axis, and they have an orbit, circling a common centre of mass in space along with any planets they have.

Measuring how quickly a star makes this orbit depends on a 150-year-old standard of astronomy called the Doppler method, which involves the same basic physics we experience when we hear changes in the pitch of an ambulance siren as it speeds toward us and then away. With stars, astronomers look for changes in the pitch, or frequency, not of sound waves, but light waves. In this way, they measure a star's speed toward or away from us, called the wobble technique in reference to the star's movement. The bigger the stellar wobble, the bigger or closer the unseen planet.

Astronomers had long known that the accuracy of the Doppler method depends on the ability to dissect light into its various colours, a technique called spectroscopy, and Prof. Walker was "the Jedi knight of spectroscopy," says UBC astronomer Jaymie Matthews, who came to the university in 1988 to conduct research with him.

Mr. Campbell was the Jedi's Luke Skywalker, an "audacious, young astronomer," says Prof. Marcy. He graduated in 1971, but returned to work with Prof. Walker as a post-doctoral researcher in 1976 after earning a doctorate at the University of Toronto. They developed a spectroscopy technique that was a spectacular 100 times more sensitive to the movement of stars.

"They were measuring the velocities of stars, for the first time in history, to plus or minus 10 metres a second," says Prof. Marcy, who began his own exoplanet search after hearing a talk Mr. Campbell gave in the 1980s. "The best that anybody at any observatory in the world had done was plus or minus one kilometre per second."

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It was the magic number for planet-hunting. Astronomers knew that massive Jupiter causes our sun to wobble at about 12 metres per second. With the Canadians' technique for using a telescope like a police radar gun, they would be able to spot the wobbles induced by Jupiter-sized exoplanets on stars elsewhere in the Milky Way.

If they were out there.

















THEY BEGAN BY HUNTING FOR JUPITER LOOKALIKES

In 1980, after a trial run on the telescope at the Dominion Astrophysical Observatory in Victoria, Mr. Campbell installed their system on the new, much larger Canada-France-Hawaii Telescope atop Mauna Kea, where he was now on staff.

Their plan was straightforward: Assuming that other solar systems existed and were like ours, Jupiter-like exoplanets would take about 12 years to orbit a star, just as Jupiter does. So they began a decade-long search of 26 stars looking for Jupiter-sized exoplanets, ones large enough, they reasoned, to perturb a star's movement to a degree visible with their telescope.

"Out of two dozen stars, and if you observed for a decade or longer, it seemed that it was a sure thing that you'd find something like Jupiter," says UBC's Prof. Matthews.

Three or four times a year, Mr. Campbell, Prof. Walker or University of Victoria astronomer Stephenson Yang, the team's other long-term member, would spend several nights atop Mauna Kea, 14,000 feet above the Pacific, searching for other worlds. They'd start just after dusk and work through the night in winter parkas, enduring altitude-induced headaches, until dawn's light overpowered the stars.

"It was deadly," Prof. Walker says of the psychological challenge. "You never knew from one night to the next if you were observing anything. You could only tell when the data were reduced, about once a year, whether we were seeing trends."

But by 1987, they believed they were seeing something no earthling had before - stellar wobbles caused by orbiting planets. That summer, at a press conference at the annual meeting of the American Astronomical Society in Vancouver, Mr. Campbell announced their preliminary results. They showed a half-dozen stellar wobbles, but one star's motion was particularly intriguing: that of gamma Cephei.

It was a fitting star for the Canadians. Bright and located 45 light years away, gamma Cephei is visible from Canada year-round, shining in the night sky near Polaris, the pole star. Mr. Campbell described how, from their detailed measurements, they'd seen that gamma Cephei had a periodic 2.5-year-long wobble. As viewed from Earth, the star appeared to move toward us and then away - evidence, they thought, of a gravitational waltz with an otherwise invisible exoplanet.

"I presided over Campbell's press conference and remember to this day the charged atmosphere and excitement that greeted his announcement," says Steve Maran, who recently retired as the long-time press officer for the American Astronomical Society.

The New York Times headline read Planets Outside Solar System Hinted. "They were calling us planet hunters. We were on the track," Bruce Campbell recalls from his island home near Victoria.

His professional colleagues weren't as impressed. One astronomer told The New York Times he wouldn't call anything a planet until he could walk on it. No one even attempted to confirm the results.

Rather than a high point, Prof. Walker says, the press conference was the beginning of the end. It increased the pressure to squeeze results from a project that, by nature, was deeply long-term.

NIO HARD EVIDENCE, NO REAL JOB

Two years later, the team still had nothing conclusive and, worse, Mr. Campbell didn't have a secure job.

A Vancouver native, he was determined to keep his family in the area, but a decade of effort had not led to a permanent position at UBC, UVic or the National Research Council's Victoria-based Herzberg Institute of Astrophysics.

The problem "had a lot to do with the fact that planet-searching was still not above the radar," Prof. Walker says. "It all started to unravel."

Further alienating Canada's astronomy establishment, Mr. Campbell publicly bemoaned the state of astronomy funding in Canada. Disheartened and distanced from the academic community, he took a final, renegade approach with the help of an influential supporter - the guru of popular astronomy and a leader in the search for extraterrestrial life, Carl

Sagan.

The two met as members of a panel at the U of T in the late 1980s, and "I remember telling Carl Sagan, 'We think we're going to be able to do this.' He was somewhat incredulous at first, but then I convinced him and he became a great friend and supporter."

Buoyed by the great man's endorsement, Mr. Campbell raised $125,000 privately to support an endowed chair in planet-hunting at UVic. However, matching funds were required from the federal government, whose guidelines at the time specified that only tenure-track professors could qualify, not an adjunct professor such as Mr. Campbell.

This was in 1991, and at the age of 42, he decided that a salary and family stability were more important to him. "When it all came to naught," Mr. Campbell says, "I decided to walk away."

When he did, he went supernova. In a final burst of anger, and a major breach of research etiquette, he erased his university computer account, deleting a decade's worth of analyzed data. Then he turned his back on the uncertainty of the stars and took up one of life's great certainties: taxes.

"It was the advent of electronic filing of tax returns in Canada that got me involved," he says, describing how he became a personal tax consultant. "Many accountants were hesitant to get into computers, and I pretty much knew how computers worked, so I had the edge there."

Although stunned by the loss of his colleague, Prof. Walker pressed ahead. It took almost a year of painstaking work for Prof. Yang, fortunately by then also UVic's computer-systems manager, and colleague Alan Irwin, to recover the lost data.

When that was done, Prof. Walker came to a conclusion about the most promising of the possible exoplanets, the one around gamma Cephei.

In a 1992 paper, he and several co-authors said the star's 2.5-year "wobble" was probably due simply to its own expansion and contraction.

"Nobody," says Berkeley's Geoff Marcy, "argued with Gordon Walker … that the data warranted the proclamation of a planet being detected."

Nobody, that is, except Prof. Walker himself. He now reveals that, after much agonizing, "I had written the paper as it being a planet."

But then, as he was sitting in his office, the recently arrived Jaymie Matthews came in, looked at the data and pointed out that the span of the supposed planet's orbit coincided with what appeared to be periods of heightened activity on the surface of the star.

"I think he had a very valid point," says Prof. Walker, who promptly cut the historic first alien planet from his paper.

"Being Canadian, we were much more cautious in announcing something like that," says Stephenson Yang. "Of course, no one would believe you anyway."

It wasn't until 2003, after assessing almost 20 years of data, that an international group of astronomers, including Prof. Walker, finally concluded definitively that, every 906 days, a planet the size of Jupiter completes its orbit around gamma Cephei.

"I feel some responsibility for this," says Prof. Matthews. "Had I not piped up, it might have gone forward … The headline would have been: 'Canadians find the first planet.'"

POLISH ASTRONOMER WOUND UP ON A STAMP

Within months of Prof. Walker's about-face, Polish-American astronomer Alexander Wolszczar announced the discovery of two Earth-sized bodies around a pulsar, the remnant of a supernova.

Completely unexpected - astronomers are still uncertain how planets survive or result from a star's detonation - they were the first planet-like objects found outside our solar system, earning Prof. Wolszczar a place on a Polish postage stamp.

Then, in 1995, Swiss astronomers Michel Mayor and Didier Queloz disclosed the discovery of 51-Pegasi b. A veteran astronomer, Prof. Mayor spent only a total of two weeks at the Haute Provence Observatory in France observing 142 stars before he and graduate student Queloz made a stunning find: a Jupiter-sized planet so close to its star that it orbited in only four days.

"Nobody, but nobody, suggested there were going to be Jupiters in few-day orbits," says Prof. Walker. "In looking for the familiar, you miss the obvious." Even worse, as a scientific referee for the Mayor-Queloz paper, he was among the first to receive the news.

In retrospect, says Prof. Marcy, the Canadians were thwarted by too small a sample of stars. "They had a technique that would have worked immediately, if only by luck they'd chosen the right stars," he says. "We now know at least 200 stars that, if they'd chosen them as their target stars, any one of them, they would have immediately seen the planet."

Ottawa native David Charbonneau, now a leading planet hunter at the Harvard Smithsonian Center for Astrophysics, says that what happened to Prof. Walker is a testament to the excruciating nature of the quest for new worlds.

"We like to imagine that the scientist looking through the microscope or telescope sees something and then they know that this is the thing they've been looking for and it's just a matter of getting the news out," he explains.

"But the point is that, when you're actually involved in a true discovery, it's a very uncomfortable process, because you really don't believe that this is the thing you saw … you start to question the data yourself."

'YOU CAN'T HELP BUT BE A LITTLE CYNICAL'

After a half-century of probing the night sky, Prof. Walker is undeterred. He is a core member of Canada's MOST space satellite team, whose project includes searching for, and studying, distant planets.

"You can't help but be a little cynical," he says, "that people can't get money for big telescopes without mentioning exoplanets."

And sadness enters his voice when discussing his old stargazing buddy. Until last month, he and Mr. Campbell lived within blocks of each other in Victoria, exchanging only pleasantries when they crossed paths.

Scientists agree the duo's contribution to the search for exoplanets is significant, but will they get the Nobel nod?

"In some sense they're worthy - Walker and Campbell began the field," says Crowded Universe author Alan Boss. "But my guess is that it will go to the folks that actually find something … This is a very competitive world, and the Nobel prizes are as competitive as it gets in science."

One way or the other, as he points one of the world's largest telescopes toward the night sky in search of alien worlds, and soon perhaps an alien Earth, Geoff Marcy readily acknowledges those on whose shoulders he's standing.

"It's a real human tragedy," he says, "but it's the way science often goes. Somebody has to stick their neck out and try a technique that everybody else thinks is wrong."

Based in Almonte, Ont., Jacob Berkowitz spent last year as journalist in residence at the Kavli Centre for Theoretical Physics in Santa Barbara, Calif. He is also the author of Out of This World: The Amazing Search for an Alien Earth (Kids Can Press, 2009).