Free Astronomy Magazine July-August 2026

12 ASTRO PUBLISHING JULY-AUGUST 2026 P lanets, like those in our solar system, form in a bottom-up process where small bits of rock and ice clump together and grow larger over time. But the heftier the planet, the harder it is to explain its formation that way. Astronomers used NASA’s James Webb Space Telescope to examine 29 Cygni b, an object about 15 times as massive as Jupiter orbiting a nearby star. They found multiple lines of evidence that 29 Cygni b in- deed formed from this bottom-up process, bringing new insights into how the heftiest planets come to be. A paper describing these findings published in The Astrophysical Jour- nal Letters. The planet formation process is broadly understood to occur within gigantic disks of gas and dust around stars through a process Webb redefines the boundary between planets and stars by NASA/ESA/CSA Laura Betz, Christine Pulliam E xoplanet 29 Cygni b, seen in this artist’s concept, is a gas giant weighing about 15 times the mass of Jupiter. Astronomers studied 29 Cygni b with NASA’s James Webb Space Telescope. They determined that it likely formed from accre- tion rather than disk fragmentation. [NASA, ESA, CSA, Joseph Olmsted (STScI)]