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3 potentially habitable planets that could have water found by Nasa

Nasa has announced the discovery of seven Earth-sized planets of which three could hold life, a find that has thrilled not just the planet-hunters but also the scientific community.

world Updated: Feb 23, 2017 11:58 IST
Malavika Vyawahare
Malavika Vyawahare
Hindustan Times, New Delhi
This illustration provided by NASA/JPL-Caltech shows an artist's conception of what the TRAPPIST-1 planetary system may look like, based on available data about their diameters, masses and distances from the host star.(AP Photo)

Nasa has announced the discovery of seven Earth-sized planets of which three could hold life, a find that has thrilled not just the planet-hunters but also the scientific community.

This is the first time three potentially habitable planets, which could have life-sustaining liquid water, have been found together.

All seven are part of the TRAPPIST-1 star system that lies about 39 light years away from us – it would take 44 million years to get there in a jet.

“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 the agency’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.”

A paper describing the discoveries was published in the journal Nature on Wednesday and a briefing held at the Nasa headquarters in Washington.

Because of the way they have evolved, these planets are potentially very water-rich, Michael Gillon, lead author of the paper and astrophysicist at the University of Liege, Belgium, said at the briefing. “Finding a second Earth is not a matter of if but when.”

For planets to support life, liquid water is a necessity. There is a band around stars where conditions are suitable for hosting liquid water. This is sometimes referred to as the “Goldilocks” zone: Not too hot, not too cold.

“The seven wonders of TRAPPIST-1 are the first Earth-size planets that have been found orbiting this kind of star,” Gillon said in a release. “It is also the best target yet for studying the atmospheres of potentially habitable, Earth-size worlds.”

The dwarf star is named after The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile.

TRAPPIST-1 is nothing like the sun. It is an ultra cool star, not because its hosts three habitable planets but because the temperature is a relatively cool -- 2550 Kelvin (K) compared to the sun’s blazing 5778 K.

It is also small, only 8% of the mass of the sun and about a tenth in radius. If the sun is a basketball, the TRAPPIST-1 would be the size of a golf ball. The lower temperature of the star means that planets close to it can host liquid water.

The seven planets uncovered in this system have been named from ‘b’ to ‘h’.

All planets that orbit around stars other than the sun are called exoplanets. Till now about two dozen planets have held out the promise of hosting life.

The latest discovery relies on observations from the Nasa’s Spitzer Space Telescope, an infrared telescope that trails Earth as it orbits the sun.

Last year, three planets of the TRAPPIST-1 system were spotted. With the help of ground-based telescopes, including the European Southern Observatory’s Very Large Telescope, Spitzer confirmed the existence of two of these planets and found five more.

Now with the help of the Spitzer, Hubble, Kepler and Nasa’s James Webb Space Telescope, to be launched next year, astronomers hope to learn more about these planets.

They will help study the atmosphere of the planets, their temperatures and surface pressures, in search for clues about life.

The search for Earth 2.0 just heated up.

First Published: Feb 23, 2017 11:58 IST