A _________________ is a cloud of dust and gas inside a galaxy.

Key Points

• A nebula is a cloud of dust and gas inside a galaxy.
• Nebulae are often regions where new stars are being formed.
• They can be composed of hydrogen, helium, and other ionized gases.
• Some of the well-known nebulae include the Eagle Nebula, the Orion Nebula, and the Crab Nebula.
• Nebulae can be observed in various colors depending on the elements they contain and the types of radiation they emit.

Additional Information

• The term "nebula" was originally used to describe any diffuse astronomical object, including galaxies beyond the Milky Way.
• Modern astronomy distinguishes between different types of nebulae, such as emission nebulae, reflection nebulae, and dark nebulae.
• Emission nebulae glow brightly due to the ionization of their gases by nearby high-energy stars.
• Reflection nebulae do not emit their own light but reflect the light of nearby stars.
• Dark nebulae are dense clouds of gas and dust that block the light from objects behind them.