Part of the gas and dust somehow collapsed causing it to compress .

When enough material is collected at the center of the disk the sun was born . Then the sun collects all the materials by strong gravity.

he sun left material then that falls to form larger and larger pieces creating the planetesimal . That's why we have planets, asteroids, comets and moons.

.After a long time, the rocky pieces becomes solid and start to move around the sun.

Only terrestrial planets like mercury, Venus, Earth, and Mars can survive close to the sun. These planet are made of silicate rocks metals.

While the rocky planets was nearby the sun, the gascous and icy material was colected further away, they was call a gas giant planet. These gas giant plants a larger than the rocky planet.