Nebulae

Nebulae are vast clouds of gas and dust in space, primarily consisting of hydrogen, helium, and other ionized gases. They are often the sites of star formation and can be visible from Earth as luminous patches of light or dark areas against the backdrop of stars. Nebulae can be categorized into several types, including emission nebulae, reflection nebulae, dark nebulae, and planetary nebulae, each characterized by different physical properties and appearances. Emission nebulae emit their own light due to ionized gases, while reflection nebulae reflect the light of nearby stars. Dark nebulae are dense regions that block light from objects behind them, and planetary nebulae are formed as a dying star sheds its outer layers, revealing a glowing shell of gas. Nebulae play a crucial role in the lifecycle of stars, serving as the birthplaces for new stars and sometimes the remnants of dying ones.