The team of astronomers which includes researchers from the UK's University of Hertfordshire and the University of California Santa Cruz, revealed that four Earth-size planets in total have been detected orbiting the sun-like star, known as the tau Ceti.
They dubbed two of the four planets "super-Earths," so-called because they have masses of around 1.7 Earth mass, larger than Earth but among the smallest planets ever detected around the nearest sun-like stars.
"[The habitable zone] is the 'Goldilocks' region around a star where the planet is not too hot or too cold and thus is able to sustain liquid water on its surface," Dr Fabo Feng, the study's lead researcher, told CNN.
Feng added that the planets are likely made "made of rocks rather than ice" which would increase the chances of them supporting life.
The researchers detected the planets by monitoring the star for tiny variations in its movement that could have been caused by a planet's gravitational pull.
"We measured the variation of the motions of the star through spectroscopic observations," Feng said.
Spectroscopy is a technique that, according to NASA's website
"measures light that is emitted, absorbed, or scattered by materials."
The variations caused by a star and those caused by a planet are very similar and the scientists had to develop a sophisticated technique to detect what Feng calls "weak planetary signals."
"Together with colleagues in UK and US," Feng said "I have detected the smallest movement of a star caused by planets."
A study published in 2013
, with research by the same team, lay the groundwork for the breakthrough.
"We realized that we could see how the star's activity differed at different wavelengths and used that information to separate this activity from signals of planets," said Dr Mike Tuomi who led the previous study, in a statement.
"We're slowly learning to tell the difference between wobbles caused by planets and those caused by stellar active surface," he said. "This enabled us to verify the existence of the two outer, potentially habitable, planets in the system."
An article on the findings is due to be published in The Astrophysical Journal.
But keen space tourists shouldn't pack their bags just yet. The planets might make less than ideal homes as researches suspect their surfaces might be constantly bombarded by asteroids and comets
Feng is, nevertheless, excited to examine the atmosphere of the planets and to use the new methods developed to find others.