Meet the 'Super-Puff' Planets

If Jupiter were as light as spun sugar, it might look a lot like this pair. Astronomers have confirmed two "super-puff" gas giants, TOI-791 b and TOI-791 c, whose densities rival cotton candy or shaving foam, per the AP. The planets, about as large as Jupiter but 35 times less dense and 140 times less dense than Earth, orbit a star roughly 1,110 light-years away in the constellation Volans, according to research published in Monthly Notices of the Royal Astronomical Society. "Only a handful of these super-puffy planets are known, and it is even rarer to find two in the same system," University of Oxford astrophysicist George Dransfield says, per NASA.

Spotted initially by citizen scientist volunteers sifting through NASA TESS data, the pair were studied for eight years by telescopes around the globe, including an Antarctic observatory, Popular Science reports. Tiny dips in starlight revealed not just their low densities but also an unusual orbital relationship: a 5:3 resonance, where the inner world completes five laps for every three of the outer. Scientists suspect such planets may have formed far from their star, building up thick hydrogen-helium atmospheres, and hope future observations—potentially with the James Webb Space Telescope—will help explain how these fragile giants came to be.