The Hunt for Moons of Rogue Planets ⚡ экспресс
Astronomers with JWST searched for exomoons around the free-floating planet WISE 0855—a chilly world just 2.3 parsecs away. Over 11 hours, NIRSpec saw no transits, but a Gaussian process helped separate a moon signal from the planet’s own variability. Artificial tests showed 96% reliability for Titan-sized satellites (0.5% transit depth). With 18 such observations, the detection chance reaches 91% if moons are as common as Galilean ones. This is the first demonstration that JWST can find moons around starless planets—like an ultrasensitive detector catching fleeting shadows.
In the vast darkness of interstellar space, the rogue planet WISE 0855 flickers with a barely perceptible heat glow, like a cooling ember. Its temperature is only a few dozen degrees above freezing — if life existed there, it would see a sunless sky, in an eternal icy haze. The James Webb telescope stared intently at this faint light for 11 hours, hoping to catch the shadow of a passing moon — as if a microscopic soot particle momentarily eclipsed a smoldering ember.
Astronomers built a model predicting the “ember’s” wavering and hunted in the data for dips — moon traces. No direct finds occurred, but the researchers tested their method by injecting artificial moons into the data. If a shadow dimmed the light by at least 0.5%, the detector triggered in 96% of cases, corresponding to a Titan-sized moon.
🎯 WISE 0855 is one of the coldest objects known beyond the Solar System: its temperature is just a few dozen degrees above freezing. If intelligent life were there, it would see a sky without any sun, perpetually shrouded in water-ice fogs.
🎬 Rogue planets with moons are almost a ready-made illustration for Isaac Asimov’s story “The Wanderer”: the characters live on a moon of an orphan planet, warmed only by internal heat.