Astronomers have identified two unusually lightweight exoplanets with densities so low they have been described as “super-puff” worlds, appearing even less dense than cotton candy, according to recent observational data from space-based and ground telescopes. The discovery adds to the growing catalogue of extreme planetary types found beyond our solar system and offers new clues about how planets form and evolve under different cosmic conditions.
The two planets, located in distant star systems, are gas-rich bodies with sizes comparable to Jupiter or Neptune but with only a fraction of their mass. Scientists believe their extremely inflated atmospheres are likely composed mainly of hydrogen and helium, stretched out by intense heat from their parent stars or internal atmospheric processes that remain not fully understood. Their low density makes them some of the most fragile planetary structures ever observed, with atmospheres so extended that they approach the boundary of space.
Researchers suggest that these “super-puff” planets challenge existing models of planetary formation, which struggle to explain how such low-mass, large-radius worlds can remain stable over long periods. One leading theory is that strong stellar radiation may be gradually stripping away their atmospheres, while another proposes that ongoing internal heating keeps their gaseous envelopes unusually expanded.
Astronomers say further observations will be needed to determine the chemical composition and long-term stability of these planets. The findings are expected to help refine theories about atmospheric physics and the diversity of planetary systems across the galaxy, highlighting just how varied worlds beyond the solar system can be compared to those in our own.
