👉 A nebula is a hypothetical structure in space, often depicted as a glowing disk or region of light. It is an imaginary object that appears to be surrounded by other objects and can vary greatly in size and shape. In astronomy, nebulas are thought to be part of the larger structure known as the circumstellar envelope (CSO). The CSO is made up of gas, dust, and stars, and it is believed that some nebulae are remnants or remnants of previously formed galaxies.
