This range is called the habitable zone - or colloquially, the Goldilocks zone.
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They were also able to extrapolate whether those super-Earths were likely to be orbiting in the habitable zone around the star.
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But over time, the telescope has been spotting more and more distantly orbiting planets including some in the habitable zone.
Fischer is going after Earth-like planets in the habitable zone.
The concept, widely used as a rule of thumb by astronomers, was codified last year by Dr. Mendez and his colleagues into a more formal Habitable Zone Distance scale.
The astronomers who will use these telescopes are particularly interested in finding any Earth-like objects in the so-called habitable zone around a star, where temperatures permit water to exist in a liquid state.
This past December, for example, NASA's Kepler space telescope confirmed its first planet in the habitable zone, a "super Earth" known as Kepler-22b that's thought to be 2.4 times as wide as our planet.
The most basic of the indexes rates a world's suitability for life based on its place within a habitable zone, which is calculated by a planet's distance from its parent star, the star's luminosity and temperature.
The habitable zone is the region of a planetary system which is neither too hot nor too cold - such that water on the surface of a planet will neither evaporate nor freeze, but instead can stay liquid.
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"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.
Researchers at the U.K.'s University of East Anglia now are working on a scale they call the "dwell time index" to calculate how much time a planet has orbited in a habitable zone, compared with the time it took life to evolve on Earth.
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.
If so, promising planets may have been sterilized by solar flares or frozen in the past, which wouldn't be reflected in present-day habitable-zone calculations.
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