An international team of astronomers has discovered two giant exoplanets with densities lower than cotton candy [1].
The discovery provides critical data on how giant planets acquire and retain massive, lightweight atmospheres. Because these "super-puff" planets defy standard density expectations, they challenge existing models of how such worlds form [2].
The collaboration was led by the University of Oxford and Université Côte d'Azur [3]. Researchers identified the planets using the Transiting Exoplanet Survey Satellite (TESS), later confirming the findings with ground-based telescopes [4].
Despite being approximately the size of Jupiter [5], the planets are remarkably diffuse. Scientists estimate their density to be around 0.1 grams per cubic centimeter [6]. This extreme lack of mass relative to their volume earns them the "super-puff" designation.
"Two newly confirmed 'super-puff' planets are so diffuse that they are less dense than cotton candy, despite being about the size of Jupiter," a ScienceDaily press release said [7].
The team announced the findings in June [8]. The nature of these planets suggests they possess an unusual composition that allows them to maintain such a large radius without the corresponding mass usually found in gas giants.
"They’re less dense than cotton candy, and they will help astrophysicists better understand the most unusual ways giant planets can form," NYT Science staff said [9].
“They’re less dense than cotton candy, and they will help astrophysicists better understand the most unusual ways giant planets can form.”
The existence of planets with such low density suggests that current astrophysical theories regarding planetary accretion and atmospheric retention are incomplete. By studying these specific 'super-puff' worlds, scientists can better determine the chemical compositions and thermal histories required to sustain a Jupiter-sized volume with minimal mass, potentially rewriting the timeline of how gas giants evolve in distant star systems.
