James Webb Solves the Mystery of the ‘Pink Planet’

The James Webb Space Telescope has helped astronomers solve a mystery surrounding the so-called “Pink Planet,” a distant world known as GJ504b.

Researchers announced on June 18 that the object’s unusual atmosphere contains clouds made of salt, a discovery that finally explains observations that scientists had struggled to understand for years.

The findings, led by Northwestern University and published in The Astronomical Journal, could change how astronomers study the atmospheres of distant planets and planet-like objects.

The discovery matters because the breakthrough is not the planet’s pink appearance but the salt clouds themselves. Until now, existing atmospheric models could not fully explain the light coming from GJ504b.

By adding salt clouds to their calculations, researchers were finally able to match what the James Webb Space Telescope observed. The finding suggests scientists may need to rethink how they interpret the atmospheres of many other worlds beyond our solar system.

How Salt Clouds Solved a Long-Standing Mystery

GJ504b was discovered in 2013 and orbits a Sun-like star about 57 light-years from Earth. Scientists classify it as a “planetary-mass companion” because it could either be a giant exoplanet or a small brown dwarf, an object that is too large to be a planet but too small to become a star.

The object is estimated to be about 25 times the mass of Jupiter and between 2.5 billion and 4 billion years old. Although its temperature is around 550 degrees Fahrenheit (288 degrees Celsius), that is considered unusually cool for a giant planet. Most giant exoplanets studied by astronomers have temperatures between 1,000 and 2,000 degrees Fahrenheit.

Its relatively cool atmosphere had puzzled scientists for years.

Multiple research teams had tried to study GJ504b from Earth but struggled to collect enough light to understand its atmosphere. Using the James Webb Space Telescope, however, researchers gathered the needed observations in just two hours.

Webb detects infrared light, which is invisible to the human eye. The telescope spread the planet’s faint light into a spectrum, creating what scientists describe as a chemical “fingerprint.” That fingerprint revealed water vapor, methane, carbon dioxide, ammonia, and several other molecules.

Even with those discoveries, the observations still did not match existing computer models until researchers added salt clouds.

“We were very surprised, because people have theorized that salt clouds might exist in the atmospheres of companions at these temperatures of, say, 500 to 700 degrees Fahrenheit, but people in general just don’t observe any kind of signatures of clouds in such temperatures,” lead author Aneesh Baburaj, a postdoctoral associate at Northwestern University’s Center for Interdisciplinary Exploration and Research in Astrophysics, told CBS News.

Why Salt Clouds Are So Important

Clouds on different planets are made from different materials depending on temperature.

On Earth, clouds are made mostly of water droplets. Jupiter has clouds containing ammonia, while extremely hot exoplanets can develop clouds made of vaporized rock, known as silicates.

GJ504b appears to fall into a temperature range where none of those cloud types fit.

Instead, researchers found that salt clouds formed the missing piece of the puzzle.

Baburaj compared them to a middle ground between the cloud types seen on cooler and hotter worlds. Once salt clouds were included in the atmospheric models, the telescope’s observations finally made sense.

The discovery suggests similar salt clouds could exist on many other cool giant exoplanets that scientists have not yet fully understood.

What the Discovery Means for Future Research

The study also highlights the James Webb Space Telescope’s ability to observe objects that older telescopes struggled to detect.

“We were really, really amazed by how easy it was to detect with James Webb, as opposed to like it had been close to impossible from the ground,” Baburaj told CBS News.

He added that Webb’s powerful infrared instruments will allow astronomers to study even colder worlds in the future.

“We will be able to detect colder and colder objects,” Baburaj said, adding that many of them may have atmospheric compositions unlike those previously studied.

Scientists believe the discovery could improve atmospheric models for exoplanets and other planetary-mass objects, making it easier to identify their chemical makeup and better understand how planets form and evolve across the galaxy.