JWST Detects Salt Clouds on 57-Light-Year 'Pink Planet' GJ504b

Q: What will finally solve the mystery of whether the 'Pink Planet' is a true planet or a failed star?

What will settle it is not the pink color or even the newly found salt clouds, but evidence of how GJ504b formed. Astronomers need to determine whether it was born in a protoplanetary disk like a giant planet or collapsed out of gas like a brown dwarf, a failed star. The new JWST data sharpen the case by showing that GJ504b’s atmosphere is unusually rich in heavy elements and contains water, carbon dioxide, methane, ammonia and deep salt clouds. That metal-rich chemistry hints at a planet-like origin, because giant planets often form in disks that can enrich them in heavier elements. But its estimated mass, about 25 times Jupiter’s, places it in the murky overlap where some objects are classified as brown dwarfs. So the decisive step will be better constraints on its formation history, tied to more precise measurements of its mass, age and composition. Researchers will compare those observations with models of planet formation and star-like collapse to see which pathway fits best. Further JWST spectroscopy, especially work that can pin down the cloud species and atmospheric structure more tightly, is expected to be central. In short, the mystery will be solved when astronomers can show not just what GJ504b looks like today, but how it came to exist.

3 articles · Updated · Space.com · Jun 18

James Webb observations of GJ504b revealed deep atmospheric salt clouds, the missing ingredient that finally made the object's unusual spectrum physically consistent.
Two hours of JWST data also identified water, carbon dioxide, methane and ammonia around the faint companion, which ground-based telescopes had struggled to capture even over a full night.
At about 550°F, GJ504b is among the coldest planetary-mass companions found from the ground; the team estimates it is 2.5 billion to 4 billion years old, helping explain its relative coolness.
Roughly 25 times Jupiter's mass and orbiting a sun-like star 57 light-years away, GJ504b still defies classification because its metal-rich makeup leaves open whether it formed like a planet or a brown dwarf.

Sources

Space.com9h ago

James Webb Space Telescope Detects Salt Clouds in "Pink Planet" GJ504b's Atmosphere

Courthouse News Service9h ago

Scientists discover salt clouds swirling around 'pink planet' | Courthouse News Service

NewsBytes9h ago

James Webb Space Telescope detects salt clouds on GJ504b

How does finding salt clouds on a gas giant reshape our models for what alien atmospheres and weather can be?

What will finally solve the mystery of whether the 'Pink Planet' is a true planet or a failed star?

JWST's Breakthrough: Potassium Chloride and Zinc Sulfide Clouds Detected on GJ504b, the "Pink Planet"

Overview

In June 2026, the James Webb Space Telescope made a groundbreaking discovery by confirming the existence of salt clouds in the atmosphere of GJ504b, a mysterious exoplanet first found in 2013. This finding, published in The Astronomical Journal, marks a major leap in our understanding of planetary atmospheres beyond our solar system. GJ504b, known for its striking color and heavy element content, has long puzzled astronomers due to its large mass and unclear classification. The detection of salt clouds not only solves a long-standing mystery but also opens new doors for studying the diversity of worlds beyond our solar system.

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