You are an astrophysicist working on a problem involving Saturn's rings and trying to figure out why the smaller ice chunks in the rings stick to larger chunks. You hypothesize that as the chunks come out of the shadow of Saturn into the sunlight, the outside of the larger chunks heats up sooner than the center and this temperature difference creates a nonuniform distribution of the charged particles in the larger chunks. (Charge polarization due to temperature differences is known as the "thermoelectric effect.") Then, even though the chunk is clectrically neutral, it has a charge separation. The small ice chunks presumably heat up uniformly all the way through and hence are not affected. Explain why small chunks gradually stick to larger ones.