Far across the dark, some 1,200 light-years from our own small blue world, a giant has been found that defies the common sense of its size. WASP-193b is larger than Jupiter, the largest of the planets in our solar system, yet it weighs so little for its bulk that it ranks as the second-lightest of more than 5,400 worlds humanity has catalogued. Reported this week in Nature Astronomy, the discovery deepens an old puzzle about so-called puffy Jupiters, and it leaves the astronomers who studied it honest about their uncertainty, since no current theory of how planets are born quite accounts for i
Scientists Discover Planet Larger Than Jupiter but as Light as Fairy Floss
Second-lightest of more than 5,400 known planets, yet bigger than Jupiter
Mark
So the headline is that it's bigger than Jupiter but light. Why does that matter?
Mimi
Because Jupiter and Saturn are much denser, and this planet is the second-lightest of more than 5,400 discovered. It doesn't fit the usual picture of a gas giant.
Mark
And the fairy floss comparison, is that just colour?
Mimi
Partly, but Barkaoui meant it literally in one sense: both are mostly light material rather than solids. For the planet, that's thought to be hydrogen and helium.
Luke
Careful there. The source says researchers suspect hydrogen and helium. That's an inference, not a measured composition.
Mimi
Fair. And the atmosphere hasn't been studied closely yet, which is exactly what they say comes next.
Mark
What's the bigger puzzle?
Mimi
Puffy Jupiters have been a mystery for 15 years, and Barkaoui calls this an extreme case. Pozuelos says it's an outlier in all the formation theories they have.
Luke
Worth noting that nobody has offered an alternative explanation yet. The reporting says classical models can't account for it, not that a new one exists.
Mark
So what's actually settled?
Luke
Its existence, confirmed last year, and that it's very low density. How it formed is unknown.
Le Pouls
- A planet bigger than Jupiter has been found to be strangely light, a contradiction that unsettles what astronomers thought they understood about giant worlds.
- Researchers say it is the second-lightest of more than 5,400 known planets, marking it as an extreme case within a class of 'puffy Jupiters' that has puzzled science for about fifteen years.
- Confirmed last year, its physical makeup took much longer to pin down, relying on ground-based telescope observations to establish its unusually low density.
- No existing formation model can comfortably place it, and the team admits it is an outlier across every theory now available.
- The next move is a closer look at its atmosphere, which could reveal the evolutionary path that produced such a fluffy giant.
Far across the dark, some 1,200 light-years from our own small blue world, a giant has been found that defies the common sense of its size. WASP-193b is larger than Jupiter, the largest of the planets in our solar system, yet it weighs so little for its bulk that it ranks as the second-lightest of more than 5,400 worlds humanity has catalogued. Reported this week in Nature Astronomy, the discovery deepens an old puzzle about so-called puffy Jupiters, and it leaves the astronomers who studied it honest about their uncertainty, since no current theory of how planets are born quite accounts for it.
A planet larger than Jupiter, the biggest in our solar system, has turned out to weigh remarkably little for its size. The international team that studied it, led by Khalid Barkaoui of the Massachusetts Institute of Technology, reported the finding this week in Nature Astronomy. The world is called WASP-193b, and it is so lightweight that it ranks as the second-lightest of the more than 5,400 planets found so far.
Barkaoui reached for a homely image to explain it: the planet is basically super fluffy, something like cotton candy, made mostly of light material such as hydrogen and helium rather than solid matter. Lying about 1,200 light-years away, it belongs to the group known as puffy Jupiters, a class that has remained a mystery for fifteen years. Its existence was confirmed last year, but establishing its true consistency took far longer and depended on ground-based telescopes.
The most candid part of the story is what it means for theory. Co-lead author Francisco Pozuelos admitted that researchers do not know where the planet fits among current formation models, since it is an outlier in all of them. Yet scientists see that as a gift: an outlier like this is well suited to studying unconventional planetary formation. The next step is its atmosphere, which may reveal the path WASP-193b has taken and, in turn, how such unusual worlds come to exist.
A planet larger than Jupiter, the biggest in our solar system, has turned out to weigh remarkably little for its size. Astronomers reported the finding on Tuesday in the journal Nature Astronomy. The world is called WASP-193b, and the international team behind the study says its density is exceedingly low.
The lead author is Khalid Barkaoui, a post-doctoral researcher at the Massachusetts Institute of Technology. He says WASP-193b is the second-lightest planet among the more than 5,400 discovered so far. The gas giants of our own solar system, Jupiter and Saturn, are much denser by comparison.
Barkaoui reached for a sweet comparison to explain it. "The planet is basically super fluffy," he said, adding that it resembles cotton candy, or fairy floss, because both are made mostly of light material rather than solids. In the planet's case, the researchers suspect that material is mainly hydrogen and helium. WASP-193b sits roughly 1,200 light-years from Earth, and NASA has produced an illustration of it.
The planet belongs to a group known as puffy Jupiters. Barkaoui described that class as a mystery that has lasted 15 years, with scientists still unsure what these planets are. In his words, WASP-193b is an extreme case of the class, and finding giant objects with such a small density is "really, really rare."
The planet's existence was confirmed last year. Working out its consistency took more time and effort, though, and relied on observations from ground-based telescopes.
What the result means for theory is where the team sounds most candid. Co-lead author Francisco Pozuelos said researchers do not know where to place the planet within the formation theories now available, because it is an outlier in all of them. He said classical evolution models cannot explain how it formed. Scientists say an outlier of this kind is well suited to studying unconventional planetary formation and evolution.
The next step, according to Pozuelos, is the planet's atmosphere. Looking at it more closely, he said, would let researchers work out an evolutionary path for WASP-193b, and that could in turn show how such unusual planets come to exist.
Citations marquantes
We cannot explain how this planet was formed, based on classical evolution models.— Francisco Pozuelos, co-lead author
The planet is basically super fluffy.— Khalid Barkaoui, lead author, MIT
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