Nebulae consist of dust and gases, primarily hydrogen and helium. They are characterized by their vast expanse, but over time, gravity gradually draws together clusters of dust and gas, leading to the formation of larger masses with increasing gravitational pull. Nebulae often serve as star-forming regions, as seen in the renowned "Pillars of Creation" within the Eagle Nebula. These regions are rich in reservoirs of dust and gas and essential for the birth of new stars. Nebulae are often mindbogglingly big and can span several light years in size. They are renowned for their stunning beauty and role as stellar nurseries, rather than for being among the coldest entities in the universe. Notably, the Orion Nebula has a temperature of around 10,000 degrees Kelvin-hotter than the surface of the Sun. Planetary nebulae have a relatively short lifespan of about 20,000 years, making them fleeting components of the stellar life cycle.