As of this month, over 5,500 exoplanets have been discovered orbiting other stars in the Galaxy. This tells us that planet formation is a universal process across the Milky Way and the majority of stars probably have at least one planet. But before you plan an extraterrestrial trip, you’ll want to pin down the best Galactic neighbourhood to visit. Not every planetary system looks the same: there are differences between the number of gas giant planets and lower-mass, mostly rocky worlds. So, where will you most likely find the kind of planet you’re after?
The difference stems from how gas giants form through core accretion. First, a mass of rocky material and ice around 10 Earth masses in size clumps together. Then, the powerful gravity of this core pulls in…
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BBC Sky at Night United Kingdom (Digital) - 1 Issue, April 2025