Scientists keep returning to one star: Proxima Centauri. It’s the nearest neighbor to our Sun, just over four light-years away, and already home to a rocky planet.
That planet, Proxima b, sits close enough to its red dwarf star for liquid water to be possible. Yet curiosity doesn’t stop there – what if another, smaller world hides nearby?
A recent study published in the journal Icarus explores that question with help from the James Webb Space Telescope (JWST).
Using Webb’s Mid-Infrared Instrument (MIRI), researchers tested whether JWST could spot an Earth-sized planet in the glare of Proxima Centauri. Their models push the telescope’s capabilities to the limit – and hint at what might come next.
Planet clues from a red dwarf
Proxima Centauri is small, cool, and dim compared with our Sun. That makes it ideal for planet searches because faint stars reveal planetary light more easily.
Astronomers already confirmed that there is one planet orbiting it, but that discovery opened more questions than it gave answers.
Red dwarfs like Proxima often erupt in intense flares that can strip away atmospheres. If Proxima b lost its envelope of gas, another world farther out might offer better conditions.
The Webb telescope’s powerful infrared eyes can peer through the dust and glare to test that idea.
Testing the telescope’s limits
The study focused on whether Webb could see the faint heat from a rocky planet roughly the size of Earth.
The team simulated observations of Proxima Centauri using MIRI’s coronagraph, which blocks a star’s blinding light so that faint companions become visible.
They tested planets between 0.1 and 1 arcsecond from the star – roughly 0.2 to 0.5 astronomical units, or half the distance from Earth to the Sun.
At that range, a planet would orbit Proxima every few months, staying within or near to the region where liquid water could exist.
Crafting realistic star scenes
A perfect simulation doesn’t exist, so the researchers built one as close as possible to reality. They added background noise from zodiacal dust, heat from the telescope itself, and small optical distortions.
The experts also modeled how accurately JWST could subtract starlight using a reference star.
The test planets varied in temperature (250 K, 400 K, and 600 K) to see how heat affected visibility. Cooler worlds mimic Earth’s warmth; hotter ones glow brighter in infrared light. Each case revealed a different challenge for the telescope’s sensitivity and contrast limits.
What Webb found at Proxima Centauri
Webb can’t easily spot a true Earth twin in orbit around Proxima Centauri. The planet’s heat signal would drown in the star’s light and background noise. But the study offered hope for slightly larger worlds – roughly 1.5 to 2 times Earth’s radius.
Warmer planets, around 400 K or more, emitted enough radiation for MIRI to detect under near-perfect conditions.
The sweet spot lies around 0.3 astronomical units, where separation from the star balances brightness and detectability. Closer planets hide behind the coronagraph’s mask; farther ones fade into the noise.
Even so, these findings mark progress. For the first time, researchers mapped Webb’s realistic limits for finding small, warm planets near the closest star to Earth.
Heat reveals hidden worlds
Most planet searches rely on visible light, but that’s a losing battle around a red dwarf. These stars barely shine in the visible range.
Their planets, however, glow with thermal infrared radiation. MIRI observes at 10 micrometers, the wavelength where such heat peaks.
At those wavelengths, an Earth-temperature planet around Proxima Centauri would appear brightest. That makes MIRI ideal for this search. Still, infrared imaging is tricky.
The telescope must stay perfectly stable. Even tiny pointing errors can bury a planet’s faint signature. The study shows how demanding those conditions are – and how close Webb already comes.
Capturing planets in view
Direct imaging skips the need for planetary transits or gravitational wobbles. It captures light from the planet itself. That light reveals not only existence but also temperature and, one day, atmospheric composition.
The team’s approach demonstrates what direct imaging could achieve with current instruments. It also shows where technology must improve.
A future telescope with a bigger mirror or an advanced coronagraph could finally isolate an Earth-sized planet around the nearest stars.
Life around red dwarfs
Red dwarfs make up most of the stars in our galaxy. If even a few of them host habitable worlds, the universe could teem with life.
Yet these stars challenge that idea. They erupt often, blasting planets with radiation. Survival depends on a strong magnetic field or a thick atmosphere.
Thermal imaging helps test that balance. A warm signal could point to a dense atmosphere trapping heat. A faint one might mean a frozen, airless rock.
Results from the Webb telescope will refine those models and prepare the way for future missions such as LUVOIR or HabEx, which are designed to study Earth-like worlds in detail.
Planets beyond Webb’s reach
Webb’s limits don’t mark an end – they outline a beginning. Even if it never spots a second planet around Proxima Centauri, its data will sharpen our understanding of nearby systems.
The telescope can measure dust, background light, and calibration precision, all vital for future designs.
Upcoming observatories could combine light from multiple telescopes, creating mid-infrared interferometers that are capable of detecting planets smaller than Earth.
This study’s simulations will guide those efforts, showing where technology must advance.
The Proxima Centauri search matters
Finding another Earth nearby would change how humanity sees itself. Proxima Centauri lies close enough that robotic probes might reach it within decades.
Knowing whether the system hosts another rocky world helps plan such missions and, more profoundly, reminds us how rare our planet might be.
This research turns that search into a measurable goal. It proves that JWST, though built for distant galaxies, can still chase the faint heat of neighboring worlds.
Each improvement brings the dream closer: to see another pale dot that might hold oceans, clouds, and perhaps life.
The search for another Earth
The study ends on a grounded note. JWST can probably detect a warm super-Earth but not a true Earth-sized twin. Still, it narrows the gap.
By combining careful modeling with new imaging techniques, researchers are learning how to spot the smallest, most elusive planets.
The search for another Earth no longer feels impossible. It feels like a matter of time – and better tools.
The researchers are affiliated with Planetary Science Institute (Tucson, Arizona), Cornell University, University of Oregon, and NASA Ames Research Center.
The study is published in the journal Icarus.
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