* Composition: Nebulae are vast clouds of gas and dust, primarily hydrogen and helium, the building blocks of stars.
* Gravity and Collapse: Within these clouds, areas of slightly higher density exist. Gravity pulls these denser regions together, causing them to collapse.
* Heat and Pressure: As the cloud collapses, the material within it becomes increasingly dense, and the pressure and temperature rise.
* Nuclear Fusion: Eventually, the core of the collapsing cloud becomes hot and dense enough for nuclear fusion to begin. This is the process where hydrogen atoms fuse to create helium, releasing immense energy and marking the birth of a star.
Therefore, nebulae provide the raw materials and conditions necessary for the formation of stars, earning them the nickname "stellar nurseries."
