What is a nebula?

• A nebula is a cloud of gas and dust in space.
  
• Some nebulae (more than one nebula) are regions where new stars are being formed, while others are the remains of dead or dying stars.
  
• Nebulae come in many different shapes and sizes.
  
• There are four main types of nebulae: planetary nebulae, reflection nebulae, emission nebulae, and absorption nebulae.
  
• The word nebula comes from the Latin word for cloud.