NASA Reveals a Jupiter-Sized Planet That's as Light as a Cotton Candy

Illustration of two super-puff planets, TOI-791 b and TOI-791 c, orbiting the Sun-like star TOI-791. NASA calls the two planets almost as big as Jupiter, but have a very small mass that makes them the most "inflated" planets ever found. Illustration: NASA/Daniel Rutter

JAKARTA - Two new giant planets have made scientists wonder. They are the size of Jupiter, but their mass is very small. Their density is even said to be similar to cotton candy.

As reported on the official website, Sunday, June 28, NASA said the findings came from data from the TESS mission or the Transiting Exoplanet Survey Satellite. The two planets are named TOI-791 b and TOI-791 c. Scientists calculated both as the most "expanding" planets ever found.

The two planets orbit a Sun-like star called TOI-791. The distance is about 1,113 light-years from Earth. One light-year is the distance light travels in one year.

TESS first detected the planet from the repeated decrease in the light of the star TOI-791. In astronomy, this pattern is called a transit, which is when a planet passes in front of its star so that the star's light appears slightly dim.

TOI-791 b is about the same size as Jupiter, but its mass is only 3.0 percent of Jupiter's mass. TOI-791 c is even larger than Jupiter, but its mass is only 5.9 percent of Jupiter's mass.

"The main reason these planets are interesting to study is that we didn't expect to find them at all," said Jon Jenkins, science lead at the Science Processing Operations Center at NASA's Ames Research Center, California.

Jenkins said the two planets were a new puzzle about how giant planets like Jupiter and super-puff planets are formed. Super-puff is a term for a large planet with a very small mass and low density.

The orbit of the second planet is also unusual. TOI-791 b takes 139 days to orbit its host star. TOI-791 c is even longer, 232 days. Planets with long orbits like this are more difficult to find because the telescope must observe for a long time.

From Earth's high orbit, TESS collected data for 1,122 days on the planet's system over a seven-year period. According to NASA, the long data helped scientists confirm the characteristics of the two planets.

Further analysis found TOI-791 b and TOI-791 c were in orbital patterns that made the two gravitationally tug on each other. That tug changed their transit times in front of the host star.

From the change in transit time, scientists calculated the mass of the two planets. The results confirm the status of TOI-791 b and TOI-791 c as super-puff planets with very low density.

"Only a few super-puff planets like this are known, and it is even rarer to find two such planets in the same system," said George Dransfield of the University of Oxford's Department of Physics, lead author of the study.

According to Dransfield, the very low density makes the two planets important to understand how planetary systems form and evolve.

Steve Howell, a NASA Ames scientist involved in the study, said the formation of large planets is believed to determine the direction of the development of a planetary system. Therefore, planets the size of Jupiter but with a much smaller mass are high-value research targets.

The next research will reveal the chemical composition of the atmosphere, the influence of rotation on the shape of the planet, the inclination of the host star, the history of orbital migration, to the process of forming super-puff planets which are still a puzzle for astronomers.

The study, published on NASA's official website, was published in Monthly Notices of the Royal Astronomical Society. The research was led by Oxford University, in collaboration with the Université Côte d'Azur or Observatoire de la Côte d'Azur and the University of Birmingham.