Astronomers have identified a pair of colossal planets, each roughly the size of Jupiter, that possess densities even lower than cotton candy. These celestial bodies, described as "super-puffs," are the most massive exoplanets discovered to date with such remarkably low densities. They orbit a star located 1,110 light-years away.
George Dransfield of the University of Oxford stated that the planets' densities are comparable to "a nice blob of shaving foam, fresh from the can." The research team reported their findings on Wednesday in the scientific journal Monthly Notices of the Royal Astronomical Society. While the planets' exact colors are unknown, Dransfield speculates they might appear white or blue, depending on atmospheric conditions.
The planets are believed to be primarily composed of hydrogen and helium. Further observations using NASA's James Webb Space Telescope are anticipated to confirm their precise chemical makeup. These two exceptionally puffy exoplanets were detected by NASA's Transiting Exoplanet Survey Satellite (TESS) over the past decade. They circle a star known as TOI-791, situated in the southern constellation Volans, which is also known as the flying fish.
Using ground-based telescopes, researchers analyzed the planets' orbits to calculate their densities from their distant location. For perspective, one light-year is equivalent to nearly six trillion miles. In comparison, Jupiter is up to 35 times denser than these two newly discovered lightweight planets.
Super-puff planets are considered uncommon in the universe. The prevailing theory suggests they form within the gas and dust disks surrounding young stars, particularly in environments with a greater abundance of gas compared to dust. Over time, these planets are thought to shed a significant portion of their mass, further reducing their density.
NASA's current catalog lists nearly 6,300 confirmed exoplanets. According to Dransfield, fewer than 40 of these are classified as super-puffs. The study of such unusual planetary systems, she noted, contributes valuable pieces to the ongoing puzzle of planet formation and enhances our understanding of humanity's place in the cosmos.