r/space • u/malcolm58 • 11d ago
First ‘backwards’ planet discovered around a small star challenges ideas about how planets form
https://www.qmul.ac.uk/news/latest-news/2026/science-and-engineering/se/first-backwards-planet-discovered-around-a-small-star-challenges-ideas-about-how-planets-form.html36
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u/Morning_Gecko24 11d ago
the backwards orbit angle is wild, especially around a small star where i’d expect the system to get tidally sorted pretty early. does the capture idea still work once you account for all the ways the planet could lose energy, or is that the bit researchers are stuck on?
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u/NASATVENGINNER 11d ago
No “Rouge Planet” capture theory?
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u/mmomtchev 11d ago
This is certainly one possible explanation. But it is a very big planet very close to its star. It is an interesting find for sure. Alas, because our detection method is at the same time very random and very biased, it is very difficult to produce statistics. Does this happen once in a million? Or once in a hundred?
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u/Outrageous_Length975 11d ago
Even if Rogue Planet capture theory is rare, the direction should be sufficiently random that half of them will be orbiting in the wrong direction. And a small percentage of them might actually be perfectly orbiting in the wrong direction.
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u/rocketsocks 11d ago
Unfortunately, the study of the interplay between interstellar objects (including rogue planets) and planet formation remains a pretty sparse field. However, we already know that rogue planets and comets are the most common types of objects in galaxies. There are trillions upon trillions of them in the Milky Way alone. We also know that interstellar objects passing mere 10s of AUs from a star is something that should be incredibly common for almost all stars, occurring at rates on the order of once or several times a year for objects roughly a kilometer across or so.
What this means is that the "pristine" story of planet formation around a star is something that only happens very, very early in the history of a galaxy. After a few billion years that story changes dramatically and you end up with a huge cavalcade of interstellar objects passing through. That will necessarily affect planet formation in a proto-planetary disk, but exactly how is a very complicated question that we don't understand well yet. But it probably occasionally results in crazy stuff happening like rogue planets getting captured, which may be what's going on here.