Solar System

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Across
  1. 2. Gravitational instability in interstellar cloud collapses to form ___.
  2. 6. The process where a comet's icy nucleus heats up and releases gas, forming a glowing coma and a tail.
  3. 7. Venus is regarded as the Earth's ___.
  4. 8. One of the known dwarf planets.
  5. 10. The fourth planet from the Sun.
  6. 11. The theoretical region located at the outermost reaches of the solar system, home to many icy bodies and comets.
  7. 12. Jupiter is primarily composed of ___, helium and putative rocky core.
  8. 14. The largest moon in the Solar system.
  9. 15. The planet known as Earth's "sister planet" due to its similar size and composition.
Down
  1. 1. trans-neptunian objects composed of ___, scattered disk and oort cloud.
  2. 3. One of the gas composition in Neptune.
  3. 4. Earth's closest celestial neighbor.
  4. 5. The region between Mars and Jupiter where many asteroids are found.
  5. 9. The celestial body that was reclassified as a "dwarf planet" in 2006.
  6. 13. The larger from the two "ice giants" in the Solar System.