Here's why:
* Molecular clouds are vast, cold, and dense regions of space where the raw materials for stars are found. These clouds are primarily composed of hydrogen and helium gas, along with small amounts of dust.
* Gravity begins to pull the particles within the molecular cloud closer together. As the cloud collapses, it becomes denser and hotter.
* This collapse eventually leads to the formation of a protostar, a hot, dense core that will eventually become a star.
So, the molecular cloud stage is the crucial starting point for the entire life cycle of a low-mass star.
