When giant planets are forming, they often gather swirling disks of gas and dust around them, called circumplanetary disks. These disks help feed the growing planet and may also contain the raw materials to build moons. But studying them has been tough because they\u2019re faint and sit very close to their host stars.<\/p>\n
Now, thanks to NASA\u2019s James Webb Space Telescope, scientists have made the first direct measurements of one such disk around a distant planet named CT Cha b, located 625 light-years away. This disk is rich in carbon and could be a moon-making zone, though no moons have been spotted yet in the data.<\/p>\n
The young star near CT Cha b is just 2 million years old and still gathering material from its surroundings. But the moon-forming disk spotted by the James Webb Space Telescope isn\u2019t part of the star\u2019s main disk; it\u2019s orbiting the planet itself, and the two are a whopping 46 billion miles apart.<\/p>\n
Why it matters: Watching planets and moons form in real time helps scientists understand how planetary systems evolve across the galaxy. Since moons may outnumber planets, and some could even host life, this marks a significant step forward. Thanks to Webb\u2019s sharp vision, we\u2019re finally entering an era where we can see moons being born, and compare these cosmic nurseries to how our own solar system formed over 4 billion years ago.<\/p>\n
Astronomers make first clear detection of a moon-forming disc around an exoplanet<\/a><\/p>\n \u201cWe can see evidence of the disk around the companion, and we can study the chemistry for the first time. We\u2019re not just witnessing moon formation \u2014 we\u2019re also witnessing this planet\u2019s formation,\u201d said co-lead author Sierra Grant of the Carnegie Institution for Science in Washington.<\/p>\n \u201cWe are seeing what material is accreting to build the planet and moons,\u201d added main lead author Gabriele Cugno of the University of Z\u00fcrich and member of the National Center of Competence in Research PlanetS.<\/p>\n Using the Mid-Infrared Instrument (MIRI) on the James Webb Space Telescope, scientists captured infrared signals from the distant planet CT Cha b. At first glance, Webb\u2019s archived data suggested the presence of molecules in the planet\u2019s surrounding disk, which could be potential building blocks for moons<\/a>. That exciting clue led researchers to take a deeper dive.<\/p>\n But spotting the planet wasn\u2019t easy. Its faint glow was hidden in the bright glare of its host star. To reveal the planet\u2019s signal, scientists used high-contrast techniques to carefully separate the star\u2019s light from the planet\u2019s, like tuning out a spotlight to see a candle flickering beside it.<\/p>\n \u201cWe saw molecules at the location of the planet, and so we knew that there was stuff in there worth digging for and spending a year trying to tease out of the data. It really took a lot of perseverance,\u201d said Grant.<\/p>\n