Why is nebula difficult to detect?

Nebulae can be difficult to detect due to their vast distances from Earth and their often faint luminosity. Many nebulae are composed of diffuse gas and dust, which can obscure them from view, especially if they are located within the plane of the Milky Way. Additionally, some nebulae emit only in specific wavelengths, such as infrared or radio, requiring specialized instruments to observe them effectively. This combination of factors makes identifying and studying nebulae a challenging task for astronomers.