Astronomers have identified two “super-puff” exoplanets, TOI-791 b and TOI-791 c, that possess densities lower than candy floss. Located 1,110 light-years away in the constellation Volans, these Jupiter-sized worlds have a density of 0.04 grams per cubic centimeter. Their discovery, facilitated by the Planet Hunters citizen science project, marks a rare instance of two extremely low-density planets orbiting the same star.
How can a planet be less dense than sugar?
These planets maintain their massive size while containing very little material, resulting in a density roughly 30 times lower than Jupiter’s 1.33 grams per cubic centimeter. The leading idea is that these worlds likely formed in the outer reaches of their solar system. In these cold regions, hydrogen and helium gas accumulated around small, rocky cores. This process created a “planet-shaped cloud” rather than a traditional solid world, leaving the planets swaddled in expansive, low-density atmospheres.
TOI-791 b and c are notable because they reach the scale of Jupiter while maintaining this extreme fluffiness.
How did researchers confirm these planets exist?
The planets were initially detected by volunteers using NASA’s TESS data. When these objects passed in front of their host star, they caused a measurable dip in light. To confirm their mass, astronomers analyzed the planets’ “misbehavior”—the slight gravitational tugs they exert on each other. By timing the early or late arrival of each transit, the team calculated the heft of the planets. Because these transits last longer than 11 hours, researchers utilized the Concordia Research Station in Antarctica to observe the full duration of the crossings during the polar night.
What is the future of exoplanet atmospheric research?
The next phase of study involves the James Webb Space Telescope. Astronomers intend to use the telescope to sniff the air for the chemical fingerprints of how they were born. This data will help clarify the composition of the hydrogen and helium layers.
Comparison: Standard Giants vs. Super Puffs
| Planet Type | Typical Density (g/cm³) | Composition |
|---|---|---|
| Jupiter | 1.33 | Not specified |
| TOI-791 b/c | 0.04 | Hydrogen/Helium |
If you are interested in contributing to real astronomical discoveries, visit the Planet Hunters website.
Frequently Asked Questions
Are super-puff planets solid?
They are, in effect, planet shaped clouds.
Why is it rare to find two super puffs in one system?
Finding even one is rare but these two orbit the very same star.
How long do these planets take to cross their star?
Each crossing drags on for more than 11 hours, which is why ground-based observations required the continuous darkness of the Antarctic winter to record the events in their entirety.
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