So, we may have been looking for alien life in the wrong place! Not long ago, scientists scouring the cosmos for Earth-like planets with the right stuff to generate life were looking around sun-like stars. It turns out that the first such planets they’ve found — seven of them — are circling something quite different: what scientists call an “ultracool dwarf” in their ultracool terminology, though in this case the reference is to the temperature of a dim star barely one-twelfth the mass of the sun.
The discovery is enormously exciting, for several reasons. One is that the little star, which in their whimsical way the scientists named Trappist-1 after the telescope in Chile initially used to study it, is a mere 40 light-years from Earth, which is next door in cosmic terms. The search for alien life can now start far sooner than anticipated, especially with new telescopes about to come into service, and some answers might be available within a decade.
Then there’s the fact that cool red dwarfs like Trappist-1 are the most common type of star, so there are probably many more potentially life-supporting worlds out there than were previously suspected. Astronomers have always presumed that other stars must have their planets, but it was only in 1995 that an exoplanet — one orbiting a star other than the sun — was confirmed. More than 3,400 of these have been discovered since.
The Trappist-1 cluster, however, is the first discovery of planets that are about the size of Earth and might have the right composition and temperature to have oceans of liquid water, and therefore, possibly, life. The planets were discovered by measuring dips in the light emitted by Trappist-1, which enabled astronomers to calculate their number and size. The next step will be to observe the planets for signs of the gases that would indicate life exists on them. In the meantime, astronomers will be checking other ultracool dwarfs to see what’s orbiting around them.
What makes this story so irresistible is the mystery and allure of the cosmos that all of us know from the first time we looked up at the stars. The article in the journal Nature announcing the discovery, signed by a large team of astronomers led by Michaël Gillon of the University of Liège in Belgium, began with the simple declaration that searching for Earth-like exoplanets is “one aim of modern astronomy.” There was no effort, and no need, to further justify the enormous commitment of resources, ingenuity, time and effort in a project that, on the face of it, has no obvious commercial or practical benefit.
There is always the possibility of collateral benefits, of course, but none could be greater than finding out whether anyone else is out there.
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