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Why did icy planetesimals form farther from the young Sun?

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asteroid Ida and its satellite, Dactyl — Small body Asteroid Ida and its satellite, Dactyl, photographed by the Galileo spacecraft on August 28, 1993, from a distance of about 10,870 km (6,750 miles). Ida is about 56 km (35 miles) long and shows the irregular shape and impact craters characteristic of many asteroids. The Galileo image revealed that Ida is accompanied by a tiny companion about 1.5 km (1 mile) wide, the first proof that some asteroids have natural satellites.

Icy planetesimals formed farther from the young Sun because of the temperature gradient within the solar nebula.12

Close to the nascent Sun, temperatures were too high for volatile substances—such as water, carbon dioxide, and ammonia—to condense into their solid ice forms. Consequently, planetesimals in the inner solar system remained primarily composed of rocky silicates and other materials with higher freezing points.12

In contrast, at distances beyond the snow line—the minimum radius from the Sun where temperatures were low enough for water to freeze—these abundant volatile substances could condense. This allowed planetesimals forming in the outer solar system to incorporate large amounts of ice, providing them with significantly more mass than their inner-system counterparts. These icy bodies eventually served as the building blocks for the massive giant planets, while many others remained as smaller remnants, such as those found in the Kuiper belt or the Oort cloud.123