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What is a nebula?

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Quick answer

A nebula is a vast cloud of gas and dust in space, often the birthplace or graveyard of stars. Some glow as nurseries where new stars form; others are the colorful remains scattered by dying stars. It's an enormous cloud of gas and dust between the stars.

Key things to understand

  1. It's an enormous cloud of gas and dust between the stars.
  2. Some are 'stellar nurseries' where gravity pulls gas into new stars.
  3. Others are the glowing remnants of dead or exploded stars.
  4. They can span many light-years across.
  5. Their colors come from different glowing gases.

People also ask

What is a nebula made of?
Mostly hydrogen and helium gas plus dust; it can glow, reflect starlight, or appear dark depending on its type.
Are stars born in nebulae?
Yes — in many nebulae, gravity pulls clumps of gas together until they grow dense and hot enough to ignite as new stars.
Why are nebulae so colorful?
Different gases glow in different colors when energized by nearby stars — hydrogen often red, oxygen blue-green.