Lin is a study in contrasts. Extremely productive, yet seemingly unhurried, intellectually expansive, yet exquisitely clear, he appears somehow casual and formal at the same time. Ask an ordinary question, and you get a thoughtful, often colorful answer. Ask a more interesting question, like why Pluto hasn't been elbowed out of the solar system, and you see Lin's eyes glow and sense ideas dancing in his mind. It's starting to look as though as many as one in five Sunlike stars has planetary companions.
Astronomers now think that planets form readily, grow quickly, and for the most part, die young.
It falls to theorists like Lin to explain their presence, their persistence, and their peculiarities. Debra Fischer, part of the group that detected the Upsilon Andromedae system, says that this discovery implies that our galaxy is teeming with planetary systems. Yet, to be honest, theoretically we have many problems forming them. The first challenge, Lin says, is finding enough matter to make a planet. Planets form from the so-called protoplanetary disks of hydrogen, helium, and other gases sprinkled with ices and cosmic dust that surround most young stars.