Planets

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Across
  1. 2. Second planet from the sun and similar in size to Earth
  2. 5. Smallest planet in our solar system
  3. 7. The time it takes a planet to complete an orbit around the sun
  4. 8. The time it takes a planet to complete one full spin on its axis (one "day" on that planet)
  5. 10. Called the "Red Planet" (iron oxide)
  6. 13. Vertical axis on HR diagram
  7. 14. Cooler stars burn this color
Down
  1. 1. Cloud of gas and dust where stars and planets form
  2. 3. Massive ball of hot gases that emits light and heat through nuclear fusion
  3. 4. Horizontal axis on HR diagram
  4. 6. Allows astronomers to classify stars and understand their life cycles
  5. 9. Atmosphere: nitrogen (78%), oxygen (21%)
  6. 11. The star at the center of our solar system
  7. 12. Hotter stars burn this color