Researchers have identified two of the puffiest giant planets ever recorded, orbiting a distant star about 1,110 light years away. These rare 'super-puff' planets have densities far below that of any known giant planets, challenging existing ideas about planet evolution.
- Planets less dense than candy floss
- Orbit a star 1,110 light years away
- Could unlock clues about planet formation
What happened
An international research collaboration led by the University of Oxford has uncovered two giant planets with remarkably low densities orbiting an F7-type dwarf star named TOI-791. These planets, called TOI-791 b and TOI-791 c, are located about 1,110 light years away in the southern constellation Volans and are roughly Jupiter-sized. However, compared to Jupiter's density of 1.33 grams per cubic centimeter, TOI-791 b and c have densities of just 0.038 and 0.047 grams per cubic centimeter, respectively, even lighter than candy floss.
The discovery resulted from data gathered through citizen-science efforts and subsequent detailed observations from various global telescopes. Scientists examined how the planets exert gravitational influence on each other, allowing precise calculation of their sizes and masses. These findings place them among only a handful of known 'super-puff' planets — giant worlds with extremely diffuse atmospheres — and uniquely, both exist within the same planetary system.
Why it feels good
Discovering these extraordinarily light planets expands our understanding of how planetary systems can vary and evolve. The extremely low densities imply these planets have large gaseous envelopes made mostly of hydrogen and helium, possibly formed far from their star in the cold regions of their original protoplanetary disc. This paints a more complex picture of planet formation than previously recognized.
Moreover, the two planets engage in a rare gravitational pattern known as a 5:3 mean-motion resonance, meaning their orbital periods are closely linked in a cosmic dance. Such dynamics provide a natural laboratory for astronomers seeking to unlock the mysteries of these unusual cosmic bodies, giving hope that further research will enrich our map of the universe’s diversity.
What to enjoy or watch next
The research team is planning follow-up observations with the James Webb Space Telescope to study the atmospheric composition of these super-puff planets. By detecting elements like carbon, nitrogen, and oxygen, scientists hope to reveal the chemical fingerprints that shaped these worlds and deepen insight into their birth environments.
This discovery also underscores the value of citizen science and international cooperation in astronomy. As new telescopes gather ever more data, the prospect of finding more unusual planets excites scientists and space enthusiasts alike—reminding us that our cosmic neighborhood still holds many wonders waiting to be uncovered.