The search for life in the universe just got a boost with a major discovery of seven Earth-like planets in our galactic back yard.
The exoplanets – so called because they are beyond our solar system — orbit a dim dwarf star called TRAPPIST-1, roughly the size of Jupiter, in the constellation Aquarius, scientists announced Wednesday.
The new worlds are less than 40 light-years away – a cosmic hop of about 235 trillion miles – and could yield clues about extraterrestrial life, astronomers said.
Three of them are in the “Goldilocks zone,” the sweet spot in the space where conditions are just right for water – and possibly life — to exist, according to NASA and a Belgian-led research team.
The smallest is about 75 percent as massive as Earth, while the largest is just 10 percent heftier than our planet. All seven occupy tight orbits, lying closer to TRAPPIST-1 than Mercury does to our sun. The orbital periods of the innermost six worlds range from 1.5 days to 12.4 days, Space.com reported.
The discovery that shook the cosmos sets a new record for greatest number of habitable-zone planets found around a single star outside our solar system, according to NASA.
“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,” he said.
Scientists said they need to study each exoplanet’s atmosphere in search of chemical signatures of biological activity to determine whether they may harbor life.
But the discovery alone suggests that there may be tens of billions of Earth-like worlds in the Milky Way, far more than previously believed.
“There are 200 billion stars in our galaxy,” said Emmanuel Jehin, a co-researcher at the University of Liege. “So do an account. You multiply this by 10, and you have the number of Earth-size planets in the galaxy — which is a lot.”
Last spring, the University of Liege’s Michael Gillon and his team reported finding three planets around TRAPPIST-1. The count is now up to seven — and Gillon said there could be more — many more. Their latest findings appear in the journal Nature.
Astronomers have traditionally focused their search for exoplanets around sun-like stars, which they would monitor for tell-tale changes in the amount of light emanating from them.
But they hit pay dirt by focusing instead on TRAPPIST-1, an ultra-cool, dim dwarf star with less than 10 percent the mass of the sun.
“The great idea of this approach was to study planets around the smallest stars of the galaxy — and close to us,” said Gillon. “That is something nobody did before us — most astronomers were focused on stars like our sun.”
Co-author Amaury Triaud, a scientist at the University of Cambridge, said the latest discovery marks a “crucial step” in finding life in the universe.
“Up to now, I don’t think we have had the right planets to find out. Now we have the right target,” he said.
In several billion years, when the sun has run out of fuel and the solar system has ceased to exist, TRAPPIST-1 will still be an infant star, astronomer Ignas Snellen with the Netherlands’ Leiden Observatory wrote in a related essay in Nature, Reuters reported.
“It burns hydrogen so slowly that it will live for another 10 trillion years,” he wrote, “which is arguably enough time for life to evolve.”
With Post Wires