Solar System

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Across
  1. 2. it spins slowly in the opposite direction from most planets
  2. 4. the age is 13.6 billion years (and counting)
  3. 7. the fast is planet, zipping around the Sun every 88 Earth days
  4. 10. the biggest planet
  5. 11. the first planet found with the aid of a telescope.
  6. 12. estimated to contain between 1.1 and 1.9 million asteroids larger than 1 kilometer (0.6 miles) in diameter, and millions of smaller ones.
  7. 13. the second-shortest day in the solar system
  8. 14. the earth's natural satellite
Down
  1. 1. the largest of Pluto's five moons
  2. 3. surface is made of water ice and so it reflects 5.5 times the sunlight than our Moon does
  3. 5. one of the largest structures in our solar system
  4. 6. is the only planet in our solar system not visible to the naked eye
  5. 7. makes a complete orbit around the Sun (a year in Martian time) in 687 Earth days
  6. 8. orbit around the Sun as are our planets.
  7. 9. A day on it 153 hours
  8. 13. the earth's biggest heat source