A world the size of Jupiter, yet light enough that it seems to defy gravity itself.
In the vast ledger of cosmic discovery, two newly confirmed worlds have arrived to humble our assumptions: planets each a thousand times larger than Earth, yet lighter than spun sugar. Found by NASA's TESS space telescope through the patient watching of starlight, these super-puff exoplanets exist at the outer edge of what physics seemed to permit. Their existence suggests that the universe harbors entire categories of worlds our models have not yet learned to imagine — and that the story of planetary formation is far stranger, and richer, than we knew.
- Two exoplanets with the volume of gas giants but the density of carnival cotton candy have shattered long-held assumptions about how large planets must behave.
- The discovery creates immediate tension in planetary science, forcing a reckoning with models that insisted bigger worlds must carry proportionally greater mass.
- NASA's TESS satellite — designed to catch the faint dimming of distant stars — is the instrument at the center of this revelation, its transit data revealing the impossible made real.
- Researchers are now working to understand how these worlds retain such vast, hydrogen-helium atmospheres without losing them to the stripping forces of space.
- The confirmed existence of these planets opens the door to an entirely new class of exoworld, one that prior surveys may have overlooked or dismissed as error.
Somewhere in the cosmos, two worlds exist that seem to break the rules. Each is roughly a thousand times larger than Earth — and yet both weigh less than a cloud of spun sugar. Astronomers have now confirmed their existence using NASA's TESS space telescope, and the discovery is forcing a fundamental rethink of how planets form and endure.
For decades, science operated on a reasonable assumption: larger planets should be denser, heavier. A world the size of Jupiter ought to carry a certain minimum mass. These two planets discard that expectation entirely. Their vast size paired with feather-light mass points to something radical — atmospheres so thick and expansive that they constitute the planet itself, with any solid core buried so deep beneath layers of hydrogen and helium that it barely registers.
The cotton candy comparison is not poetic license. It is a statement of density. These planets occupy a similar density range to that spun-sugar confection, meaning a world the apparent size of Jupiter could weigh almost nothing by planetary standards. TESS detected them through the transit technique — watching for the subtle dimming of starlight as a planet crosses its host star — then researchers combined that size data with mass estimates to arrive at their extraordinary conclusion.
The implications reach beyond these two worlds. Their existence suggests some planets can hold onto massive gaseous envelopes across vast stretches of time, resisting the forces that would normally strip lighter elements away. It also hints that super-puff planets may be far more common across the galaxy than anyone predicted. Each such discovery adds another unexpected data point to an emerging portrait of planetary diversity — one that keeps proving stranger, and more wondrous, than our models had prepared us for.
Somewhere in the cosmos, two worlds exist that seem to violate the basic rules of physics. They are each roughly a thousand times larger than Earth—massive enough that you could fit our entire planet inside them many times over. And yet they weigh less than a cloud of spun sugar. These are the super-puff planets, and astronomers have just confirmed their existence using NASA's TESS space telescope.
The discovery marks a turning point in how scientists understand planetary formation. For decades, astronomers have operated under certain assumptions about how planets work: bigger objects should be denser, heavier. A world the size of Jupiter ought to have a certain minimum mass. But these two planets shatter that expectation entirely. Their enormous size paired with their feather-light mass suggests something radical about their composition—they are wrapped in atmospheres so thick, so expansive, that they dominate the planet's entire structure.
TESS, the Transiting Exoplanet Survey Satellite, has been scanning the sky since its launch, watching for the telltale dimming of starlight that occurs when a planet passes in front of its host star. This method, called the transit technique, allows astronomers to infer a planet's size. By combining that measurement with other observational data, researchers can estimate mass and density. What TESS revealed in these two cases was extraordinary: planets with the radius of gas giants but the density of something you could almost float on water.
The comparison to cotton candy is not merely poetic. It is a literal statement about density. Cotton candy—that spun sugar confection from carnivals—has a density of roughly 5 kilograms per cubic meter. These newly discovered planets have densities in a similar ballpark, which means that if you could somehow place one on a scale, it would weigh less than you might expect for something so visibly enormous. The contrast is jarring: a world the size of Jupiter, yet light enough that it seems to defy gravity itself.
What makes these planets so puffy is their atmospheres. Unlike Earth, which has a relatively thin shell of air, or even Jupiter, which has a substantial but still proportional atmosphere, these super-puff worlds are dominated by their gaseous envelopes. Hydrogen and helium—the lightest elements in the universe—make up the bulk of their volume. The actual solid or liquid core, if one exists, is buried so deep beneath layers of gas that it contributes almost nothing to the planet's overall mass. The atmosphere is the planet.
This discovery has immediate implications for how astronomers think about planetary formation and evolution. It suggests that certain planets can retain massive atmospheres over long periods of time, resisting the gravitational stripping that would normally cause lighter gases to escape into space. It also hints at the existence of an entire class of worlds that previous models did not adequately predict. As telescopes become more sensitive and surveys like TESS continue their work, astronomers may find that super-puff planets are far more common than anyone suspected.
The two worlds join a small but growing catalog of exoplanets that challenge conventional wisdom. Each discovery adds another data point to the emerging picture of planetary diversity across the galaxy. What was once thought impossible—a planet so large yet so light—is now confirmed fact. And that shift in understanding is precisely what drives science forward.
The Hearth Conversation Another angle on the story
When you say these planets are lighter than cotton candy, are we talking about the same density, or is this more of a metaphor?
It's literal. Cotton candy has a density of about five kilograms per cubic meter. These planets are in that same ballpark. You could theoretically float one if you had a bathtub large enough.
That's almost impossible to visualize. How does a planet that size stay together?
Gravity. Even though the planet is light, it still has enough mass to hold itself together. The real question is how it keeps such a massive atmosphere from drifting away into space.
And that's what makes this discovery important—it tells us something about how planets hold onto their air?
Exactly. It suggests that under certain conditions, planets can retain enormous atmospheres for billions of years. We didn't have a good model for that before.
So when TESS found these, was it a surprise, or were astronomers already looking for something like this?
A bit of both. TESS was designed to find exoplanets, but the sheer puffiness of these two—the extreme ratio of size to mass—that caught people off guard. It's the kind of thing that makes you rethink what's possible.