The Solar System

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Across
  1. 2. a large disk shaped cloud of dust and gas formed as the solar nebula rotated faster and flattened out
  2. 4. the process of adding mass in the formation of the planets by collisions between planetesimals
  3. 5. The different shapes of the illuminated side of the moon as seen from Earth
  4. 6. a round depression in the surface of a planet or moon caused by the impact of a meteoroid
  5. 8. A model of the solar system in which all planets revolve around the Sun
  6. 9. The low, flat plains of basalt on the moon formed by ancient lunar lava flows
  7. 11. the type of nebula that can eventually collapse to form one or more stars with a planetary system
  8. 12. a very sparse sphere of comets encircling the solar system out to a distance of 50,000 AU
  9. 14. a disk made of many small particles of rock and ice in orbit around the sun
  10. 15. a chunk of rock that travels through the solar system
  11. 18. A model of the solar system in which all planets revolve around Earth
  12. 20. the name of the wide belt beyond Pluto's orbit where objects mostly made of ice and rock orbit the sun
Down
  1. 1. a relatively small body in space that revolves around a planet
  2. 3. the four planets closest to the sun which are similar in structure to Earth
  3. 5. asteroid-sized bodies in the protoplanetary disk from which planets are formed by accretion
  4. 7. a tide at the new or full moon when the change between high and low tide is the greatest
  5. 10. small, rocky solar-system bodies mostly found between Mars and Jupiter
  6. 13. the regular rise and fall of water in the oceans
  7. 16. Event that occurs when the shadow of one body in space falls on another
  8. 17. a tide at the first or last quarter moon when the change between high and low tide is the smallest
  9. 19. a unit of measurement that is equal to the distance from the Earth to the Sun (149,598,000 km)