Final answer:
The sun contracted first as a gas ball, followed by the formation of planets and moons through accretion and condensation within the solar nebula.
Step-by-step explanation:
The sun and the planets did not form at the same time, but rather in a sequence of events. According to the solar nebula theory, the sun formed first as a contracting gas ball. As the gas cloud collapsed under its own gravity, it conserved angular momentum and formed a spinning disk of dust and gas called the solar nebula. Within this nebula, solid particles called planetesimals began to form through the process of accretion and condensation. These planetesimals then accumulated to form the planets and moons.
The remaining debris in the solar nebula can still be seen as comets and asteroids today. The process of formation of our solar system is believed to have taken place around 4.5 billion years ago.