In our own Solar System, the gas giants sit far from the Sun; Jupiter is five times further out than Earth, Saturn nearly ten. For a long time, astronomers assumed that was simply how planetary systems worked. Then we started finding planets around other stars, and some of them broke every rule. Hot Jupiters are gas giants similar in size to Jupiter but orbiting their stars at a fraction of the distance, some completing a full orbit in just a few days. Temperatures on their surfaces can reach thousands of degrees. They are exotic, extreme, and until recently, deeply puzzling. These hot gas giants are the bullies of their planetary system. They sit almost on top of their parent stars, blisteringly hot and gravitationally dominant. Anything smaller that dares share their neighbourhood gets scattered into oblivion. Which is why, when astronomers discovered a mini Neptune quietly orbiting inside one in 2020, they were somewhat baffled.…