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A type of interstellar cloud that is so dense that it obscures the light from objects behind it. These are often sites of future star formation, as they contain the cool molecular hydrogen and dust needed to form new stars.

A region of ionized hydrogen (protons and electrons) created by the ultraviolet light from hot, young stars. H II regions are indicative of recent star formation and contribute to the cycle of star birth by disrupting their environment.

The coldest and densest type of interstellar cloud, mainly composed of hydrogen molecules. They are the stellar nurseries of the galaxy, where stars are born from the collapse of regions within the cloud under their own gravity.

Dense dust clouds that reflect the light of nearby or embedded stars. They do not emit their own light but may be associated with star-forming regions, often seen around young stars that are still in the process of gathering mass.

A cloud of ionized gas emitting light of various colors. These nebulae are often the site of star formation, particularly when they are associated with giant molecular clouds.