lighter than shaving foam, fresh from the can
Across a distance of 1,110 light-years, two Jupiter-sized worlds have been found that weigh almost nothing — less dense than cotton candy, lighter than shaving foam. Discovered through NASA's Tess satellite and confirmed by ground-based observatories, these so-called 'super-puff' planets belong to one of the rarest categories in the known cosmos, with fewer than 40 confirmed among nearly 6,300 exoplanets. Their existence invites a deeper question humanity has long carried: what are the true boundaries of how worlds are made, and where does Earth sit within that vast and still-unfolding architecture?
- Two Jupiter-sized planets orbiting a star over a thousand light-years away have been confirmed as the least dense worlds of their size ever found — lighter, pound for pound, than shaving foam.
- Super-puffs are extraordinarily rare, and the discovery of two at once, both at such extreme low density, sends a jolt of urgency through the planetary science community.
- Jupiter, the giant of our own solar system, is up to 35 times denser than these two featherweights — a comparison that stretches the imagination of what a planet can even be.
- Researchers believe these worlds formed in gas-rich protoplanetary disks and have been slowly shedding mass ever since, but the mechanics of that process remain poorly understood.
- NASA's James Webb Space Telescope is now being directed toward these planets to confirm their chemical composition and sharpen our models of how planetary systems are born.
Two planets the size of Jupiter have been found orbiting a star 1,110 light-years away, and what sets them apart is not their scale but their near-weightlessness. They are less dense than cotton candy — lighter, by measure, than fresh shaving foam. Astronomer George Dransfield of the University of Oxford led the team that identified the pair using data from NASA's Tess satellite, with findings published in the Monthly Notices of the Royal Astronomical Society.
These worlds belong to a category called super-puffs — planets so diffuse they seem to defy intuition. Fewer than 40 are known among the nearly 6,300 confirmed exoplanets, making each discovery significant. Jupiter, the largest planet in our solar system, is up to 35 times denser than these two new worlds. Dransfield suspects they are likely white or blue in appearance, their color shaped by cloud cover, with compositions dominated by hydrogen and helium.
Super-puffs are thought to emerge from the gas-rich disks surrounding newborn stars, accumulating vast envelopes of material that they gradually shed over time. The process is not yet well understood, which is precisely why these planets matter. Ground-based telescopes helped calculate their orbits and, from there, their density — confirming just how extreme these objects are.
NASA's James Webb Space Telescope will now conduct follow-up observations to pin down the planets' exact chemical makeup. Each new super-puff found adds a rare data point to humanity's effort to understand how planets form — and what place our own world holds in the broader, still-mysterious architecture of the cosmos.
Two planets the size of Jupiter have turned up in the southern sky, and they are so insubstantial that they would float. Astronomers studying data from NASA's Tess satellite discovered the pair orbiting a star 1,110 light-years away—a distance so vast that light from that star takes over a millennium to reach Earth. What makes these worlds remarkable is not their size but their weight. They are less dense than cotton candy. They are lighter, pound for pound, than shaving foam fresh from a can.
George Dransfield, an astronomer at the University of Oxford, led the team that made the discovery. She and her colleagues reported their findings this week in the Monthly Notices of the Royal Astronomical Society. The two planets represent something genuinely rare: the largest super-puffs ever found with such low density. For context, Jupiter—the heavyweight of our own solar system—is as much as 35 times denser than these two featherweights.
Super-puffs are thought to form in the swirling disks of gas and dust that surround newborn stars, in regions where gas vastly outnumbers solid material. Over time, these planets shed much of what they initially accumulated, becoming progressively more wispy and insubstantial. The process is still not fully understood, which is why these discoveries matter. Dransfield suspects the two planets are probably white or blue in color, their appearance determined by whether clouds shroud their surfaces. Their composition is likely dominated by hydrogen and helium, though confirmation will require further observation.
That confirmation is coming. NASA's James Webb Space Telescope, the most powerful observatory ever built, will conduct follow-up observations to determine the exact chemical makeup of these distant worlds. The data from Tess, which has been scanning the sky for a decade, provided the initial detection. Ground-based telescopes then helped researchers calculate the planets' orbits and, from that, their density.
The discovery underscores how much remains unknown about planetary systems beyond our own. Nearly 6,300 exoplanets have been confirmed to date, yet fewer than 40 are super-puffs. These two newly identified worlds are among the most extreme examples of that already exotic category. Dransfield framed the significance plainly: studying these rare and unusual systems adds crucial pieces to humanity's understanding of how planets form and what role Earth and its neighbors play in the broader cosmos. Each discovery of this kind pushes the frontier of what we know about the universe's architecture.
Citas Notables
These two planets have densities comparable to a nice blob of shaving foam, fresh from the can.— George Dransfield, University of Oxford
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.— George Dransfield, University of Oxford
La Conversación del Hearth Otra perspectiva de la historia
Why does density matter so much when we're talking about planets we'll never visit?
Because density tells you what a planet is made of and how it formed. A planet as light as shaving foam is telling you something fundamental about its history—it lost almost all its heavy material. That's a clue to how planetary systems evolve.
So these aren't actually made of cotton candy or foam?
No. They're mostly hydrogen and helium—the lightest elements. But the density comparison is the point. It's a way to make the impossible tangible. You can't hold a Jupiter-sized planet, but you can imagine shaving foam.
Why are super-puffs so rare if they form naturally around young stars?
We don't fully know yet. Maybe they're rare because the conditions have to be just right—lots of gas, not much dust. Or maybe they don't stay super-puffs for long. They might lose their atmospheres and become something else.
What does the Webb telescope add that Tess couldn't see?
Tess found them and measured their orbits. Webb can analyze their light in detail—break it down into wavelengths that reveal what elements are actually there. It's the difference between knowing something exists and understanding what it is.
Does finding these change how we think about our own solar system?
It does. It shows us that Jupiter and Saturn, which seemed extreme to us, are actually quite ordinary. There are planets out there that are far stranger. That reframes what we thought was normal.