What is a Nebula?

• A. Giant clouds of Hydrogen and Helium in space, where new stars are born, and the remnants of dying stars
• B. A planet
• C. A galaxy
• D. A meteor

Answer: (A)

Nebulae are giant clouds of gas and dust in space—mostly hydrogen and helium. Under gravity, parts of a nebula can collapse to form new stars, so they act as stellar nurseries. They also include material from dying stars, seen as planetary nebulae or supernova remnants. Some nebulae glow because hot young stars ionize the gas (emission nebulae), while others shine by reflecting starlight (reflection nebulae). The other options describe completely different objects: planets, galaxies, or meteors.