New simulations suggest gas giants can build roughly 10-Earth-mass solid cores in about 200,000 years when icy pebbles drifting inward from the outer disk grow into planetesimals before being swept up by embryos. Instead of relying mainly on inefficient direct pebble capture, the process concentrates solid material between roughly 6 and 9 astronomical units, where relatively small planetesimals can feed planetary cores rapidly. The model offers a possible solution to the long-standing problem of forming Jupiter-like planets before their gas disks disappear or their growing cores migrate too close to their stars. Building something as massive as Jupiter presents planetary scientists with a timing problem. A giant planet must assemble a large solid core while plenty of hydrogen and helium still surrounds its young star, yet conventional planet-building processes can take too long. Computer simulations now suggest a possible shortcut. Icy particles born far from a young star can drift inward, collide and grow into larger bodies that pile up in a relatively narrow region of the protoplanetary disk. Planetary embryos there can then consume …