New hope of finding life beyond Earth
7 Earth-like planets, 3 in star's 'habitable zone', found
CAPE CANAVERAL : Astronomers have found a solar system with seven Earth-sized planets, three of which circle their parent star at the right distance for liquid water to exist on the surface, bolstering the prospect of discovering extraterrestrial life, research published on Wednesday showed.
The star, known as Trappist-1, is a small, dim celestial body in the constellation Aquarius. It is about 40 light years away from Earth, close by astronomical standards, but still about 44 million years away at the cruising speed of a commercial passenger jet.
Researchers said the proximity of the system and the large size of its planets proportional to its small star, makes it a good target for follow-up studies. They hope to scan the planets' atmospheres for the possible chemical fingerprints of life.
"The discovery gives us a hint that finding a second Earth is not just a matter of if, but when," US National Aeronautics and Space Administration chief scientist Thomas Zurbuchen said at a news conference.
The discovery, published in this week's issue of Nature, builds on the discovery of three planets around Trappist-1. They are among more than 3,500 planets discovered outside the solar system, or exoplanets.
"This is the first time that so many Earth-sized planets are found around the same star," said lead researcher Michael Gillon of Belgium's University of Liege.
Researchers have focused on finding Earth-sized rocky planets with the right temperatures so that water, if any exists, would be liquid, a condition believed to be necessary for life.
The diameter of Trappist-1 is about 8 percent of the sun's size. That makes its Earth-sized planets appear large.
From the vantage point of telescopes on Earth, the planets' motions regularly block out bits of the star's light. Scientists determined the system's architecture by studying these dips.
Because Trappist-1 is so small and cool, its "habitable zone" is very close to the star.
Three planets are positioned for liquid water, Mr Gillon said. "They could have some liquid water and maybe life."
Even if the planets do not have life now, it could evolve.
Trappist-1 is at least 500 million years old. The sun, by comparison, is about halfway through its estimated 10-billion-year lifespan.
In a few billion years, when the sun dies and our solar system has ceased to exist, Trappist-1 will still be an infant, astronomer Ignas Snellen, wrote in a related essay in Nature.
"It burns hydrogen so slowly that it will live for 10 trillion years,arguably enough time for life to evolve." - REUTERS