The Formation of the Solar System

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Across
  1. 2. A cloud of dust and gas from which the planets and sun formed is now known as the solar ____.
  2. 8. groupings of a star and orbiting planets (2 words)
  3. 9. He developed the nebular hypothesis of the origin of the solar system. He proposed that matter in the solar system began as separate particles.
  4. 10. The ______ planets (Mercury, Venus, Earth, and Mars) have rocky surfaces with features such as mountains, valleys, and craters. They also have few or no moons and molten metal cores.
  5. 12. He used mathematics to refine the nebular hypothesis.
  6. 13. a space object that (1) orbits a star, (2) is large enough to have a nearly spherical shape, and (3) has “cleared the neighborhood” around its orbit
  7. 14. this forms when a nebula collapses, the temperature and pressure increase over time as particles in the nebula collide and clump together. It at the center of the nebula, surrounded by gaseous and rocky debris.
  8. 15. the comparison between mass and size
Down
  1. 1. rocky bodies that orbit larger bodies, such as planets, dwarf planets, and asteroids
  2. 2. He published his theory that all matter in the universe attracted all other matter through a force he called gravity. His theory explained the motion of the planets around the sun.
  3. 3. _____ measurements measure an exact distance or size
  4. 4. the attractive force that keeps objects in orbit
  5. 5. Protoplentary ____ is a flat cloud of gas and dust orbiting a newly formed star, from which planets may eventually form. The prefix proto- means “earliest” in Greek.
  6. 6. The ______ planets (Jupiter, Saturn, Uranus, and Neptune) have thick atmospheres composed of hydrogen and helium. Only the center layers of these gas giants and ice giants are solid. Their large masses provide enough gravity to hold more moons than terrestrial planets.
  7. 7. the first person known to use a telescope to observe the stars and planets. He supported the idea that Earth is not the center of the universe but that Earth and the other planets circle the sun.
  8. 11. _____ measurements compare a size or distance to something else.