A family moves into a cramped apartment in the city center. If the move was calm, relatives might have moved in with them. But if the family was evicted from their old home by a storm, they'll end up alone in the new place. That's roughly how astronomers figure out the fate of hot Jupiters — giant planets that orbit right next to their star, sometimes closer than Mercury is to the Sun.

Out of more than 500 confirmed hot Jupiters and about 2000 additional candidates, only ten have close planetary neighbors. That's very few. If such giants smoothly migrated toward the star through the gas-and-dust disk, neighbors would have survived more often. So in most cases, the path was different — abrupt and destructive: the planet first moved onto an elongated orbit, then the star pulled it in, and along the way it shoved other planets aside.

Astronomers analyzed data from the TESS space telescope from its first five years of operation and estimated how often hot Jupiters have close transiting neighbors. The result is about 8%—this is the lower limit on the fraction of giants that migrated calmly or were born in place. Comparison with other detection methods shows that hot Jupiters with neighbors are likely to orbit in the same plane as their companions, but they pass slightly more often across the edge of the star's disk, hinting at a slight tilt in their orbits.

Why does this matter? If we understand the most common route by which hot Jupiters reach their orbits, we'll get a better picture of how planetary systems are structured overall, and how often Earth-like worlds can survive near such giants. The rare neighbors of hot Jupiters are not just a statistical quirk; they are a window into the turbulent past of distant worlds.