NASA’s Transiting Exoplanet Survey Satellite (TESS) has identified two “puffiest” worlds ever found, TOI-791 b and TOI-791 c, which researchers describe as having a consistency similar to cotton candy. According to NASA, these worlds possess the size of gas giants but hold only a fraction of their mass.
What makes these “cotton candy” planets unique?
These planets stand out due to their extreme ratio of volume to mass. TOI-791 b is nearly the same size as Jupiter, yet it contains only three percent of its mass. Its sibling, TOI-791 c, is even larger than Jupiter but accounts for just 5.9 percent of its mass. George Dansfield of Oxford University’s Department of Physics, who led the research team, notes that while we’re only aware of a handful of super puffy planets, finding two in the same system is even rarer.
Did you know? TESS has cataloged 7,931 exoplanet candidates since its launch in 2018, with 897 already confirmed. The mission covers an area of the sky 400 times larger than the Kepler mission.
How do scientists measure the mass of such airy planets?
Researchers calculated the mass of these planets by observing how they interact with each other. Because the two planets are locked in an orbit around their star that has them tugging on each other, they exert a gravitational tug on one another. According to NASA, this interaction causes variations in the timing of their transits—the moments they pass in front of their host star—which scientists used to derive their mass. This data was compiled over a seven-year period, totaling 1,122 days of observation.
Why is this discovery important for future space research?
Understanding these low-density worlds provides insight into how planetary systems evolve. NASA Ames research scientist Steve Howell explains that large planet formation is believed to drive the evolution of planetary systems. Studying these Jupiter-sized, but far less than Jupiter-mass, planets is of high value. Future research will focus on analyzing the chemical composition of their atmospheres, how their spin affects their shape and, ultimately, how “cotton candy” planets like them form.
Comparison: Typical Gas Giants vs. Cotton Candy Planets
| Planet | Size (Relative to Jupiter) | Mass (Relative to Jupiter) |
|---|---|---|
| TOI-791 b | ~1.0 | 3% |
| TOI-791 c | >1.0 | 5.9% |
Frequently Asked Questions
- Why are they called “cotton candy” planets? The term describes their extremely low density, which is comparable to the airy structure of cotton candy.
- How long did it take to confirm these planets? Researchers utilized 1,122 days of data collected by the TESS spacecraft over seven years.
Explore more: What other secrets is TESS uncovering in our galaxy? Read more about the TESS mission objectives and join our newsletter for the latest updates on exoplanet discoveries.
