An Indian astronomer using the James Webb Space Telescope (JWST) has discovered one of the strangest worlds ever observed: a mysterious pink planet-like object wrapped in clouds made of salt.
Known as GJ504b and nicknamed the “pink planet” for its distinctive pink color, the object has mystified scientists since its discovery in 2013. Now, after more than a decade of failed attempts to study it in detail, Webb has finally revealed what lies hidden within its atmosphere.
Located about 57 light-years from Earth, GJ504b orbits a Sun-like star that lies in a gray area between a giant planet and a brown dwarf. With a mass about 25 times that of Jupiter, astronomers classify it as a “planetary mass companion” rather than a conventional planet.
What makes this discovery remarkable is not only the unusual color of the world, but also the composition of its atmosphere.
Using Webb’s powerful infrared instruments, researchers led by Northwestern University were able to capture the faint light coming from GJ504b and break it down into a spectrum, essentially a chemical fingerprint of its atmosphere. Observations revealed water vapor, methane, carbon dioxide and ammonia.
But the data didn’t make sense at first.
Computer models struggled to explain the spectrum unless scientists added a theoretical component beforehand: clouds made of salt particles.
“We tried three different types of clouds, and salty clouds were the best,” said lead researcher Anish Babraj. “When we took into account salt clouds, the results became physically possible.”
This discovery provides some of the first direct evidence that salty clouds can form in the atmospheres of extremely cold planetary bodies. Scientists have expected the existence of such clouds for more than 15 years, but until now they have never been able to confirm their existence.
Unlike most directly imaged exoplanets, which can reach temperatures of 1,000 to 2,000 degrees Fahrenheit, GJ504b is relatively cool at about 290 degrees Celsius, comparable to the temperature inside a baking oven.
The study also suggests that the piece may be rich in heavy elements, although its origins remain unclear. Scientists are still debating whether it formed like a giant planet around a star or appeared like a miniature star itself.
In addition to solving the mystery of the pink planet, this discovery demonstrates Webb’s extraordinary ability to study cold, dim worlds that were previously beyond the reach of the largest ground-based telescopes.
For astronomers searching for increasingly Earth-like worlds, GJ504b’s salty skies may be a glimpse of discoveries to come.
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