Granted, the M83 galaxy is gorgeous.
But the picture is just a prelude, a test image taken by the new planet-hunting SPECULOOS telescopes.
The four instruments—activated, calibrated, evaluated—now await New Year’s Day 2019, when the real search starts.
From then on, rather than gleaming galaxies, SPECULOOS glimpses only the haziest of shadows, cosmic silhouettes trillions of miles away.
The goal, however, is crystal clear.
“We want to detect potentially habitable Earth-sized planets,” says Michael Gillon, the project’s principal investigator.
The SPECULOOS telescopes begin with the smallest of targets: ultra-cool dwarf stars, approximately one-tenth the size of the Sun and less than half as hot. “Very tiny and very cold,” says Gillon.
Also very close—all are just dozens of light years from Earth (one light year is about six trillion miles).
“That’s our neighborhood,” Gillon says.
The telescopes aren‘t powerful enough to actually see planets. Instead, SPECULOOS will point at their stars, searching for transits—eclipse-like events, when a planet moves between the star and telescope.
“When a fraction of a star is hidden by the planet, we detect the drop in brightness,” Gillon says. Confirm that through repeat observations, and astronomers can infer a world is there.
The small size of the stars helps. Ghostly blurs become slightly more discernible. “We focus on these tiny objects,” he says, “because when the planet passes in front of them, the signal we detect will be stronger.”
SPECULOOS will look at 1,000 stars. Gillon, an astronomer at the University of Liège in Belgium, hopes to discover “dozens of planets” within a few years.
The telescopes reside in the eeriest of locales—at the Paranal Observatory in Chile’s remote Atacama Desert, an otherworldly milieu of brownish soil and rock evocative of Mars. With virtually no rain, Atacama is one of the driest spots on Earth.
But the perfect place to see stars.
“Conditions there are unique,” says Gillon. “There are nearly no clouds and no city lights.
“Earth-sized” and “Earth-like” are two different things. The SPECULOOS worlds, certainly, are not our twins. “To say Earth-like is a bit too extreme,” Gillon cautions.
Typically, ultra-cool dwarf stars bombard orbiting planets with stellar flares and deadly radiation for billions of years. Landscapes might be sterilized, atmospheres obliterated; without an atmosphere, liquid surface water can’t exist.
“It’s possible these planets were fried—cooked by the star when it was bigger and hotter,” he says.
Scientists presume these worlds are also tidally-locked. That‘s when half the planet forever faces its host star; the other side is perpetually dark.
Understates Gillon: “This is not Earth-like.”
And now, the kicker.
About 232 trillion miles away, in the constellation Aquarius, is the TRAPPIST-1 system—an ultra-cool dwarf star clinching seven cramped Earth-sized worlds, all with rocky surfaces.
Gillon’s team discovered three of the planets in2015 With help from NASA’s Spitzer Space Telescope, they found the remaining four in 2017.
Then a 2018 study indicated two of the TRAPPIST-1 planets, both orbiting in the habitable zone, could hold liquid water.
Now there‘s a template, Gillon thought: a multiplanet system with perhaps a life-friendly world or two. TRAPPIST-1, he says, suggests such systems are common. With the new telescopes, he hopes to find TRAPPIST-1 analogues—lots of them.
“Maybe,” he speculates, “the frequency of potentially habitable planets around ultra-cool dwarf stars is really, really large.”
If so, then “SPECULOOS should detect plenty of systems like TRAPPIST-1.”
SPECULOOS is strictly a discovery machine. The finer points—like whether or not a planet is habitable—are left to others. NASA’s new James Webb Space Telescope, scheduled for a 2021 launch, will analyze the atmospheres of exoworlds; a “significant fraction” of the SPECULOOS discoveries “will be well suited for the James Webb,” Gillon says. Should the Webb find oxygen on a world, it’s a hint—though not a certainty—that the planet is alive.
In the meantime, says Gillon, SPECULOOS will “build the largest possible catalog of Earth-sized planets for Webb.”
That catalog is essential. So little is known; the search for extraterrestrial life has barely begun. Some call it quixotic. But most of all, it‘s a slog.
“It might take centuries to get the final answer,” Gillon says. “The hope is what motivates us.” Even in perhaps the most parched place on Earth, hope springs eternal.
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Given, the M83 galaxy is
However the image is simply a start, a test image taken by the brand-new planet-hunting SPECULOOS telescopes.
The 4 instruments– triggered, adjusted, assessed– now wait for Brand-new Year’s Day 2019, when the genuine search begins.
After That, instead of shining galaxies, SPECULOOS peeks just the haziest of shadows, cosmic shapes trillions of miles away.
The objective, nevertheless, is clear.
” We wish to spot possibly habitable Earth-sized worlds,” states Michael Gillon, the job’s primary private investigator