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Three newly discovered planets are seen circling the star HR 8799 in the constellation Pegasus. ((Christian Marois/National Research Council/Keck Observatory))

An international team of scientists led by a Canadian researcher has discovered three planets circling a star they say is 130 light years away. 

The discovery is a crucial step toward finding a habitable planet like Earth, said astrophysicist Christian Marois, who works with the National Research Council's Herzberg Institute in Victoria.

Images captured by the team show three likely planets appearing as pale specks of white near a star named HR 8799. They are probably not visible to the average eye, but are to experienced astronomers.

Two groups of researchers surveyed nearly 100 young stars over the past four years in search of photographable planets, but didn't find any until they came across HR 8799 last year.

Using the Hubble Space Telescope and two ground telescopes, scientists were able to capture images of the exoplanets, or planets beyond the solar system, which are considered to be very young at 60 million years of age.

The gaseous planets are also far from inhabitable, glowing hot at nearly 800 C.

But the images are an exciting step toward understanding "if there are other planets like Earth, and potentially life out there," said astronomer Bruce Macintosh of the Lawrence Livermore National Laboratory in California, the base for one of two teams of out-of-this-solar system photographers that were working on the project.

It's only a matter of time before "we get a dot that's blue and Earth-like," he said.

It's 'the Holy Grail': Montreal astronomer

The discovery is monumental for astronomers, who consider this "the Holy Grail," said Andrew Fazekas, president of the Montreal branch of the Royal Astronomical Society of Canada.

More than 300 planets have been catalogued by astronomers to date, but they were measured by gauging changes in gravity, speed or light around the star, not by taking their pictures, he said.

NASA's space sciences chief Ed Weiler said the actual photos are critical, comparing it to hunting for elusive elephants.

"For years we've been hearing the elephants, finding the tracks, seeing the trees knocked down by them, but we've never been able to snap a picture," he said. "Now we have a picture."

Whether these are the first exoplanet photos remains a point of dispute. Other astronomical photos have been taken but their contents haven't been confirmed as planets.

Alan Boss, an exoplanet expert at the Carnegie Institution of Washington, and Harvard exoplanet hunter Lisa Kaltenegger both said more study is needed to confirm these photos are proven planets and not just brown dwarf stars.

But NASA said the new pictures are the most convincing evidence to date.

The findings appear in Thursday's edition of Science Express, the online edition of the research journal Science.

With files from the Associated Press