Astronomers using NASA's James Webb Space Telescope have reported possible evidence of clouds made of salt on the exoplanet GJ 504 b, a gas giant orbiting a sun-like star about 57 light-years from Earth. The planet, first discovered in 2013, is known for its pinkish hue, which may be linked to its atmospheric composition.
The study, led by researchers at the University of Tokyo and published in the journal Astrophysical Journal Letters in 2026, analyzed infrared light from the planet's atmosphere. The data suggest the presence of silicate and salt particles, including sodium sulfide, which could form clouds at high altitudes. This marks the first time such compounds have been identified on a world outside our solar system.
GJ 504 b is about four times the mass of Jupiter and has a temperature of around 500 degrees Fahrenheit (260 degrees Celsius). Its pink color is thought to result from the scattering of light by these cloud particles, similar to how Earth's sky appears blue. The planet orbits its star at a distance of about 43 astronomical units, roughly 1.5 times the distance of Neptune from the Sun.
The findings provide new insights into the diversity of exoplanet atmospheres and the types of clouds that can form on alien worlds. Further observations with Webb are planned to confirm the composition and structure of these clouds.
