• Self-luminous, gaseous objects that fuse elements
  • Obtain energy from nuclear fusion
  • Considered a star when it can sustain itself through nuclear reactions (making its own energy)
  • How long it takes a star to form depends on its mass

Distance from the Earth

  1. Parallax
  2. Using brightness measurements
    • Look at the star, determine it's color spectrum (good indication of it's actual brightness)
    • Compare the actual brightness with the apparent brightness, they can determine the Distance
      • It's apparent brightness will be dimmer

Space Astronomy