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Scientists discover deformed exoplanet shaped like a rugby ball

It's kind of like the conehead of planets.

Amanda Kooser
Freelance writer Amanda C. Kooser covers gadgets and tech news with a twist for CNET. When not wallowing in weird gear and iPad apps for cats, she can be found tinkering with her 1956 DeSoto.
Amanda Kooser
2 min read
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Exoplanet WAP-103b is shaped more like a rugby ball than a beach ball. The tidal forces of its host star pull it out of round.

ESA

In our solar system, we're used to our planets looking very round, like beach balls. But there's a solar system out there that hosts a very different sort of planet, one that a team of astronomers says is shaped more like a rugby ball. 

WASP-103b resides in the Hercules constellation along with a star (named WASP-103) that's hotter and bigger than our own sun. The planet takes less than a day to orbit its star, and that lack of elbow room is why it has such an unusual shape. "This is the first time that the deformation of an exoplanet has been detected, offering new insights into the internal structure of these star-hugging planets," the European Space Agency said Tuesday in a statement.

The team used fresh data from ESA's Cheops space telescope, along with observations from NASA's Hubble and Spitzer telescopes, to better understand what's going on with WASP-103b. On Tuesday, the scientists published a paper with their findings in the journal Astronomy & Astrophysics.

The exoplanet is twice the size of Jupiter and likely has an internal structure similar to that of our solar system's familiar gas giant. Much like our moon exerts tidal forces on Earth, WASP-103b experiences extreme tidal forces due to its star tugging on it. The researchers were able to discover the planet's deformity thanks to Cheops' ability to study in detail a dip in brightness when WASP-103b moves in front of its star.

An ESA infographic compares WASP-103b to Jupiter and highlights how it is bent out of shape.  

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This ESA infographic shows how exoplanet WASP-103b compares with Jupiter.

ESA

WASP-103b appears to be very inflated compared with Jupiter, which may be due to heating of the planet caused by its star. "If we can confirm the details of its internal structure with future observations, maybe we could better understand what makes it so inflated," said the lead author, astronomer Susana Barros. "Knowing the size of the core of this exoplanet will also be important to better understand how it formed."

The cause of the planet's inflation isn't the only mystery. It may be moving away from its star, rather than being pulled in closer over time as would be expected. It'll take further observations to figure this one out, but it may be resisting the fate of some similar planets, which are eventually consumed by their stars.

Our understanding of exoplanets has expanded considerably in recent years as powerful telescopes locate and study the distant worlds. While much is still unknown about WASP-103b, the level of detail already revealed through Cheops is remarkable.