At a Glance

Astronomers have discovered seven Earth-sized planets around a single star.Three of these planets are in what is called the "habitable" zone.Located in the TRAPPIST-1 star system, the planets are some 40 light years away in the Aquarius constellation.

Using NASA's Spitzer Space Telescope, scientists have found a new solar system filled with seven Earth-like planets surrounding a single star, three of which might be habitable, the agency announced Wednesday.

The three planets are located in what is called the "habitable zone" –the area around a parent star where a rocky planet is most likely to have liquid water, according to.

represent the “holy grail for planet-hunting astronomers," because they sit within the “temperate zone” and are the right temperature to allow alien life to flourish, the researchers said. They added that the planets, located some 40 light-years away in the constellation Aquarius, are capable of having water, a necessity to life.

“This discovery could be a significant piece in the puzzle of finding habitable environments –places that are conducive to life,” said Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate in Washington. “Answering the question 'are we alone?' is a top science priority and finding so many planets like these for the first time in the habitable zone is a remarkable step forward toward that goal.”

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No other star system has ever been found to contain so many Earth-sized and rocky planets of the kind thought to be necessary to sustain life, and because the system is relatively close to Earth, astronomers say they can study the planets’ atmospheres relatively easily.

“This system is going to be one of the best laboratories we have for understanding the evolution of small planets,” says Zachory Berta-Thompson, an astronomer at the University of Colorado Boulder.

The researchers might soon be able to find evidence of life on the planets, they said.

“The discovery of multiple rocky planets with surface temperatures which allow for liquid water make this amazing system an exciting future target in the search for life," said Chris Copperwheat of John Moores University.

The press conference that was shrouded in mystery for several days focused on details of "exoplanets," which are planets that orbit stars other than the sun.

Exoplanets are significant because they are key to the discovery life on other planets.

The first earth-like planet to be discovered was, a rocky planet that lies within the so-called "habitable zone" and is similar in size to Earth. Since then, the Kepler space telescope has located many more such planets.

"This is the most exciting result I have seen in the 14 years of Spitzer operations," Sean Carey, manager of NASA's Spitzer Science Center at Caltech/IPAC in Pasadena, California, said during Wednesday's press conference. "Spitzer will follow up in the fall to further refine our understanding of these planets so that the James Webb Space Telescope can follow up. More observations of the system are sure to reveal more secrets.”

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