Astronomers have discovered an unexpected surprise on the famous “Pink Planet,” a strange world known as GJ504b.
Using the powerful James Webb Space Telescope (JWST), scientists found that the object is surrounded by salty clouds and has an atmosphere filled with unusual chemicals.
GJ504b was first discovered in 2013. It orbits a sun-like star about 57 light-years away from Earth. Despite its nickname, scientists are not completely sure whether it is actually a planet.
At around 25 times the mass of Jupiter, it lies in the gray area between giant planets and brown dwarfs, which are objects too small to become stars.
Because of this uncertainty, astronomers simply call it a “planetary-mass companion.”
The object is especially interesting because it is extremely cold compared with other directly imaged giant planets.
Most of these worlds have temperatures between about 540 and 1,100 degrees Celsius.
In contrast, GJ504b has a temperature of only about 290 degrees Celsius, similar to the heat inside an oven used for baking bread.
Scientists believe the object has cooled down over billions of years. The new study estimates that GJ504b is between 2.5 billion and 4 billion years old.
For years, astronomers tried to study the Pink Planet using some of the largest telescopes on Earth, but the object was simply too faint. The glare from its much brighter host star made it nearly impossible to examine.
The James Webb Space Telescope finally changed that. In just two hours of observations, JWST collected enough light from GJ504b to create a spectrum, which is like a chemical fingerprint made from light. By studying this spectrum, scientists can identify the molecules present in an object’s atmosphere.
The data revealed a rich mixture of chemicals, including water vapor, methane, carbon dioxide and ammonia.
However, when researchers tried to recreate the atmosphere using computer models, something did not make sense. The models only matched the observations if the atmosphere contained strange and unrealistic features.
The mystery was solved when the team added clouds to their simulations. The best explanation was the presence of clouds made from salts. These salt clouds likely hide the deeper parts of the atmosphere and change the light that escapes into space.
This is the first direct evidence that salt clouds play an important role in shaping the atmosphere of such a cold world.
The observations also suggest that GJ504b contains unusually high amounts of heavy elements. Yet scientists still do not know exactly how it formed. It may have developed like a giant planet, or it may have formed more like a small failed star.
The discovery shows just how powerful the James Webb Space Telescope is and offers a glimpse of the strange and exotic worlds waiting to be explored in our galaxy.
