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).