Across
- 3. an interstellar cloud of dust, hydrogen, helium and other ionized gases
- 4. Planet terrestrial planets are Earth-like planets (in Latin, terra means "Earth") made up of rocks or metals with a hard surface, making them different from other planets that lack a solid surface. In our solar system, there are four terrestrial planets, which also happen to be the four closest to the sun: Mercury, Venus, Earth and Mars
- 7. a smaller clump of gas, dust, and rocky material that may combine with other clumps to form larger masses, including planets
- 10. the point in the orbit of a planet, asteroid, or comet at which it is furthest from the sun
- 11. the coming together and cohesion of matter under the influence of gravitation to form larger bodies
- 12. a regular oval shape, traced by a point moving in a plane so that the sum of its distances from two other points (the foci) is constant
- 13. the turning of a body around an internal axis
- 15. a substance formed when two or more chemical elements are chemically bonded together
Down
- 1. the movement of one body around another body (planets around the sun, moons around planets, etc.)
- 2. a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction
- 5. an attractive force existing between any two masses that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them
- 6. a substance consisting of atoms which all have the same number of protons (the same atomic number)
- 8. Planet a large planet composed mostly of gases, such as hydrogen and helium, with a relatively small rocky core. The gas giants of our solar system are Jupiter, Saturn, Uranus and Neptune
- 9. the point in the orbit of a planet, asteroid, or comet at which it is closest to the sun
- 14. smallest component of an element that shares the chemical properties of the element