THE STARS

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Constellations

• Divide sky up into sections (“group of stars”)


• Today we use 88 constellations that completely cover the sky. These constellations cover the entire sky, both in the northern and southern hemispheres, and help us map the stars.


• The constellations you can see in the sky change with the seasons because the Earth orbits around the Sun. Some constellations only show up in certain months, while others can be seen year-round.

Star formation

• Start with a molecular cloud


• Molecular cloud collapses under gravity


• Eventually cloud becomes dense and hot enough to ignite nuclear fusion:
  
  Birth of protostar