super-puff planets – Astronomers have discovered two giant exoplanets—so low in density they’re likened to shaving foam—that orbit a star 1,110 light-years away. The rare “super-puff” worlds challenge expectations about how planets like Jupiter form, and follow-up observations wit
When astronomers measure the heft of distant worlds. density is usually a straightforward clue: compress the material enough and you learn what it’s made of. This time, the numbers refused to cooperate. The pair of newly identified giant exoplanets are so puffy that researchers say they’re lighter than cotton candy—super-puffs roughly the size of Jupiter. yet with densities comparable to a blob of shaving foam fresh from the can.
The planets orbit a star 1,110 light-years away, in the southern constellation Volans—known as the flying fish. “These two planets have densities comparable to a nice blob of shaving foam. fresh from the can. ” George Dransfield of the University of Oxford wrote in an email. Dransfield and her team reported the findings Wednesday in Monthly Notices of the Royal Astronomical Society.
What makes them especially striking is how their lightness compares with the standard reference point of Jupiter. Jupiter is as much as 35 times denser than these two lightweights. The contrast is part of what turns a new detection into a scientific headache: the planets appear to be among the lightest known planets of their size.
Dransfield suspects the atmospheres are likely white or blue, depending on whether the skies there are cloudy. She also expects the planets are probably mostly hydrogen and helium, but says it will take follow-up observations by NASA’s Webb Space Telescope to confirm their chemical makeup.
The detection started with NASA’s TESS satellite, which found the planets over the past decade. Researchers then used telescopes on Earth to study the planets’ orbits and determine their density from the distance of 1. 110 light-years away. A light-year is nearly 6 trillion miles—an enormous yardstick that underscores how indirect this kind of measurement can be.
The orbital measurements also don’t match what many observers would expect for worlds that are this massive. NASA said one planet takes 139 days and the other takes 232 days to circle the host star.
Super-puffs are considered rare in the cosmos. and the discovery adds another data point to a puzzle that already has scientists uneasy. The basic idea is that these planets may form around the disk of gas and dust around a newborn star. in regions where there’s more gas than dust. Over time. they’re thought to shed much of that material—stripping down even more—yet the result is still an end product that looks unusually puffed up.
In 2024. researchers found another super-puff planet about 1. 200 light years from Earth and called it a “cosmic mystery.” Now the newest pair seems to deepen the same riddle. “The main reason these planets are interesting to study is that we didn’t expect to see them at all. ” said Jon Jenkins. the science lead for the Science Processing Operations Center at NASA’s Ames Research Center in California’s Silicon Valley. “They represent a puzzle for us to solve about how giant planets like Jupiter and the super-puffs form.”.
NASA’s tally of worlds outside our solar system currently stands at nearly 6,300 confirmed, and fewer than 40 are super-puffs. Dransfield said that gives researchers a narrow window: “Ultimately. by studying exotic systems containing rare planet types. we add further pieces to the puzzle of planet formation and learn more about our place in the cosmos.”.
For now, the planets’ whisper-light densities and their long orbits are the headline. The next step will be even more demanding: using NASA’s Webb Space Telescope to pin down what’s in their skies and confirm whether hydrogen and helium dominate as expected. If the chemistry matches the lightness. the super-puffs may still be rare—but they’ll be less mysterious. one measurement at a time.
exoplanets super-puff planets NASA TESS NASA Webb Space Telescope planet density Volans George Dransfield Jon Jenkins astronomy planet formation