Astronomers have discovered two of the fluffiest planets ever found.
These giant worlds are so light and airy that they are actually less dense than cotton candy.
The discovery gives scientists a rare chance to learn how unusual planets form and change over time.
The two planets are called TOI-791 b and TOI-791 c. They orbit a young star about 1,110 light-years away from Earth in the southern constellation Volans.
Even though both planets are about the same size as Jupiter, they contain much less material packed into that space.
To understand just how strange they are, it helps to compare their densities. Jupiter has an average density of about 1.33 grams per cubic centimeter. Earth is even denser at around 5.5 grams per cubic centimeter.
But TOI-791 b has a density of only 0.038 grams per cubic centimeter, while TOI-791 c has a density of 0.047 grams per cubic centimeter. Cotton candy has a density of about 0.05 grams per cubic centimeter, making these planets even fluffier.
Scientists believe the two planets formed together from the same cloud of gas and dust surrounding their young star.
They also move in a rare orbital pattern called a 5:3 resonance. This means that every time the inner planet completes five trips around the star, the outer planet completes almost exactly three.
As they orbit, the planets gently pull on each other with gravity. These tiny tugs slightly change the timing of when each planet passes in front of its star. By carefully measuring these timing changes, astronomers were able to estimate the planets’ masses and confirm their extremely low densities.
The planets were first spotted by volunteers taking part in Planet Hunters TESS, a citizen science project that allows members of the public to search for new planets using data from NASA’s Transiting Exoplanet Survey Satellite.
Professional astronomers then confirmed the discovery using several telescopes around the world.
One telescope played a particularly important role. The Antarctic Search for Transiting ExoPlanets (ASTEP) telescope, located at Concordia Station in Antarctica, was able to observe the planets during the Antarctic winter.
Because the Sun stays below the horizon for months, astronomers could watch each transit continuously for more than 11 hours. These are the longest complete planetary transits ever recorded from a ground-based telescope.
Only four other known planetary systems contain more than one super-puff planet, making TOI-791 an exceptionally rare find.
Scientists are still trying to explain why these planets became so bloated. One leading idea is that they are surrounded by enormous atmospheres made mostly of hydrogen and helium. These thick gas layers may have formed when the planets were born far from their star, where cool conditions allowed gas to gather around a solid core.
The research team now plans to study the planets using the James Webb Space Telescope. By examining the chemicals in their atmospheres, including carbon, nitrogen, and oxygen, scientists hope to uncover new clues about how these strange, fluffy worlds came to exist.
Source: KSR.
