Superpuff Planet: TOI-791 c
Today's planet is a Neptune-like gas giant with an extraordinarily low density.
Illustration provided by NASA, done by Daniel Rutter
Discovery Method: Transit via NASA's TESS mission
Distance from Earth: 1,113 light years
TOI-791 c was discovered by NASA's TESS Mission alongside TOI-791 b. The two planets have extraordinarily low densities, earning them the nickname "super-puffs." To put the planet's density into perspective, TOI-791 c is larger than Jupiter, but barely has 5.9% of its mass.
Super-puff planets are extremely rare and it was a shock for NASA scientists to find two in the same system together. “They represent a puzzle for us to solve about how giant planets like Jupiter and the super-puffs form,” said Jon Jenkins, the science lead for the Science Processing Operations Center at NASA’s Ames Research Center in California’s Silicon Valley.
Further analysis into the planet and its twin revealed that TOI-791 c and TOI-791 b have orbital patterns that actually allow them to actually exert gravitational pull on each other and affect the other's orbit. The variation in orbit was used by scientists to actually gauge the density of either planet.
With more data and studying, super-puff planets like TOI-791 c may be able to give further knowledge into planetary evolution and interaction.
Arezu Sarvestani. “NASA’s TESS Mission Reveals the ‘Puffiest’ Planets Ever Found.” NASA Science, 25 June 2026, https://science.nasa.gov/missions/tess/nasas-tess-mission-reveals-the-puffiest-planets-ever-found/. Accessed 3 Aug. 2026.
“TOI-791 c - NASA Science.” NASA Science, 17 July 2026, https://science.nasa.gov/exoplanet-catalog/toi-791-c/. Accessed 4 Aug. 2026.