What is a Nebula?

About Nebula:

• A nebula is a giant cloud of dust and gas in space.
• Some nebulae (more than one nebula) come from the gas and dust thrown out by the explosion of a dying star, such as a Supernova.
• Other nebulae are regions where new stars are beginning to form. For this reason, some nebulae are called "star nurseries."
• How do stars form in a nebula?
  • Nebulae are made of dust and gases—mostly hydrogen and helium.
  • The dust and gases in a nebula are very spread out, but gravity can slowly begin to pull together clumps of dust and gas.
  • As these clumps get bigger and bigger, their gravity gets stronger and stronger.
  • Eventually, the clump of dust and gas gets so big that it collapses from its own gravity. 
  • The collapse causes the material at the center of the cloud to heat up-and this hot core is the beginning of a star.
• Nebulae exist in the space between the stars—also known as interstellar space.
• The closest known nebula to Earth is called the Helix Nebula. It is approximately 700 light-years away from Earth.
• Nebulas come in many shapes and sizes and can be further divided into several subcategories, including planetary nebulas, supernova remnants, dark nebulas, and emission nebulas. 

Red Spider Nebula:

• It is a planetary nebula located 3,000 light-years from Earth and can be found in the constellation of Sagittarius. 
• It harbours one of the hottest stars known, which heats the gas around it to form shockwaves 62 billion miles (100 billion km) high.