nebula

A nebula is a vast cloud of gas and dust in space, often acting as the birthplace of new stars. These luminous or dark regions can vary greatly in size and shape, with some glowing brightly due to nearby stars illuminating them, while others appear as dark patches blocking light from behind. Nebulae are fundamental to the life cycle of stars, providing the raw material for stellar formation. They are observed across the universe in various forms—such as emission, reflection, and dark nebulae—and are a key focus of astronomical study for understanding cosmic evolution.