"We now know the rate of occurrence of habitable planets around the most common stars in our galaxy, " said Prof Charbonneau.
BBC: Exoplanets near red dwarfs suggest another Earth nearer
Kepler is designed to find out how common habitable planets are, but its target stars are too distant for their planets to be studied directly.
Seager called the discovery of the three planets "a huge milestone, " but her excitement is tempered because potentially habitable planets have been announced in the past and there's currently no way to get more details, given how far away they are.
"We now think there is a new class of ocean-covered - and possibly habitable - planets in solar systems unlike our own, " said Dr Raymond.
BBC: NEWS | Science/Nature | Earth-like planets may be common
Dr. THOMMES: We had have ordered a few percent of systems that where the giant planets at least resemble the architecture in our own system, as to whether we would then have terrestrial planets in the habitable zone, the chances of that actually aren't too bad, because the terrestrial planets, we think, they kind of sprout like mushrooms pretty much anywhere.
Finding habitable earth-like planets around other sun-like stars has never been an easy task.
FORBES: Earth-Like Exo-Moons Can Lurk Well Beyond Planetary Habitable Zones, Say Astronomers
Earth-like planets in habitable zones form in the presence of large amounts of water, the researchers suggest.
BBC: NEWS | Science/Nature | Earth-like planets may be common
The team concluded that about one of every three known planetary systems could harbour Earth-like planets in habitable zones further out than the Hot Jupiters.
BBC: NEWS | Science/Nature | Earth-like planets may be common
"Planets in the habitable zones of stars must be everywhere, " she said.
Fischer is going after Earth-like planets in the habitable zone.
On the plus side, the ability to directly detect light from a planet closer to the size of Earth than a Jupiter-sized gas giant is a positive step forward in our ability to learn more about planets that might be habitable.
This raises the possibility that planets like ours orbiting in habitable zones could be covered in oceans - providing all the key constituents required for life.
BBC: NEWS | Science/Nature | Earth-like planets may be common
However, just like the other planets, we haven't seen or tested the atmospheres of any of these planets, so whether they're habitable remains theoretical.
According to Dr Lissauer, about 50 of the 1, 200 or so candidate planets (if planets they be) are orbiting in the habitable zones of their parental stars.
Measuring at two-thirds the size of our sun, this cosmic lantern is orbited by a total of five planets, three of which are too close to be habitable for life.
ENGADGET: NASA's Kepler discovers three potentially habitable planets
"What's particularly interesting is four new planets - less than twice the size of Earth - that are potentially in the habitable zone, the location around a star where it could potentially have liquid water to sustain life, " Dr Burke told BBC News.
"Assuming that 1:10, 000 are similar to the Earth would give us 5, 000, 000 such planets, " added Tuomi, who led teams reporting the discovery of several potentially habitable planet candidates this year, including an exoplanet orbiting the star Tau Ceti just 11.9 light-years from Earth.
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