While dust is a crucial component in the formation of planetary systems, it's not the *first* ingredient.

Here's why:

* Stars are the foundation: Planetary systems form around stars. The gravitational pull of the newly formed star is what attracts and gathers the material that will eventually become planets.

* Dust is part of the protoplanetary disk: This disk is formed from the leftover material from the star's formation, which includes gas and dust.

* Dust as building blocks: The dust particles in the protoplanetary disk collide and stick together, eventually forming larger and larger objects, ultimately leading to planets.

So, the correct sequence is: star formation → protoplanetary disk formation (including dust and gas) → planet formation.