Astronomers have directly observed two exoplanets shedding their outer layers into space for the first time. The observations provide a rare look into the interiors of these planets, which has remained challenging even for Earth.
K2-22b, a Neptune-sized rocky exoplanet, orbits its star in just nine hours. The intense heat, exceeding 3,320°F (1,826°C), causes its rocky surface to vaporise, forming a comet-like tail. The James Webb Space Telescope (JWST) captured this phenomenon.
A separate team using the Transiting Exoplanet Survey Satellite (TESS) discovered BD+054868Ab, the nearest disintegrating exoplanet to Earth. It is losing mass rapidly, with two distinct tails—one carrying sand-sized particles and another containing finer grains.
The material escaping from BD+054868Ab extends 5.6 million miles (9 million kilometres), covering almost half of its orbit. Scientists estimate it is shedding about a moon’s worth of mass every million years.
JWST detected carbon dioxide and nitric oxide in K2-22b’s atmosphere—elements usually linked to icy bodies rather than terrestrial planets. This suggests the planet may have formed farther from its star before migrating inward.
Researchers estimate BD+054868Ab will fully disintegrate within one to two million years. This is a short timescale compared to most planets, which typically exist for billions of years.
The findings from both studies have been published as preprints and are undergoing peer review. Scientists consider these planets unique cases that provide insight into planetary evolution under extreme conditions.