WHEN Luke Skywalker’s uncle forbids him to join the Space Academy in Star
Wars, Luke storms out of the house shielding his eyes against the glare of
two setting suns. But can planets form in binary star systems? Yes, say two
researchers who claim that such planets are more than science fiction.
When dust particles in the disc around a young star collide, they stick
together, eventually forming objects about a kilometre across. Such
“planetesimals” can then merge, but only if their relative velocities are low.
If they are too fast, the planetesimals break up into smaller pieces when they…
