Unit 3 Test Review

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Across
  1. 2. Unit The average distance between Earth and the Sun, about 93 million miles.
  2. 4. A very large planet made mostly of gases like hydrogen and helium, with no solid surface you could stand on.
  3. 7. The point in a planet's orbit when it is closest to the Sun.
  4. 8. The correct model of our solar system that places the Sun at the center, with all planets orbiting around it.
  5. 10. Belt, A ring-shaped region beyond Neptune filled with icy objects and dwarf planets.
  6. 13. Nebula The giant cloud of gas and dust that collapsed and spun to form our Sun and solar system about 4.6 billion years ago.
  7. 14. Small chunks of rock, ice, and dust that clumped together in the early solar system and eventually grew into planets through collisions and gravitational attraction.
  8. 15. A rocky object that orbits the Sun, usually found in the asteroid belt between Mars and Jupiter.
  9. 17. The invisible force that pulls objects toward each other.
  10. 20. A meteoroid that survives its trip through the atmosphere and actually hits the ground.
  11. 21. Cloud, A giant, invisible sphere of icy objects that surrounds our entire solar system, much farther out than the Kuiper Belt.
  12. 22. Planet, A small, round object that orbits the Sun but hasn't cleared other objects from its orbital path
Down
  1. 1. Planet A rocky planet with a solid surface similar to Earth.
  2. 3. Force The force that keeps an object moving in a circular path instead of flying off in a straight line
  3. 5. The bright streak of light you see in the sky when a meteoroid burns up in Earth's atmosphere.
  4. 6. The Sun and everything that orbits around it, including planets, moons, asteroids, comets, and dust.
  5. 7. Thin, flat circles of ice, rock, and dust that orbit around some planets.
  6. 9. A "dirty snowball" made of ice, dust, and rock that develops a bright tail when it gets close to the Sun and the ice starts to melt.
  7. 11. The old, incorrect model that placed Earth at the center of the universe, with everything else orbiting around Earth.
  8. 12. The way an object appears to move when you look at it from different positions.
  9. 16. A small piece of rock or metal floating in space, usually broken off from asteroids or comets.
  10. 18. The point in a planet's orbit when it is farthest away from the Sun.
  11. 19. The curved path an object takes as it travels around another object in space, like how Earth travels around the Sun.