Fomalhaut b is a directly imaged exoplanet.

Fomalhaut is a nearby star surrounded by a broad debris ring. In 2008, Hubble images revealed a faint source moving near that ring, and NASA announced Fomalhaut b as the first exoplanet directly imaged in visible light.

The object was unusual from the start. It was bright in visible Hubble images but difficult to detect in the infrared, where a young giant planet should emit heat. Its orbit and relationship to the debris ring also produced competing explanations, including models in which a smaller planet was surrounded by dust.

Later Hubble observations provided the decisive evidence. By 2020, the source had faded and become spatially extended instead of remaining compact. Gáspár and Rieke showed that this behavior fits an expanding dust cloud produced by a collision between large planetesimals. Radiation pressure from Fomalhaut would then push the smallest dust grains outward while the cloud became fainter and more diffuse.

The correction is therefore a reclassification rather than a simple failed detection. Hubble did observe a real object associated with Fomalhaut’s planetary system, but the object called Fomalhaut b is now best understood as transient collision debris rather than a planet. Its nature had been disputed for years; what changed in 2020 was that the source itself evolved in a way a persistent planet could not explain.