Vocabulary Review

2. The attractive force between any two objects with mass; what holds the solar system together.
4. A huge ball of gas, held together by gravity, that produces light and heat through nuclear fusion.
8. Numerical data gathered through measurements and observations.
10. The spinning of Earth on its axis, which causes day and night.
12. Rocky object that orbits the Sun, mostly found in a belt between Mars and Jupiter.
13. A large, round celestial body that orbits a star and has cleared its orbital path.
17. Describes the Moon when the illuminated portion is growing larger as seen from Earth.
18. A star and all the objects that orbit around it, held by its gravitational pull.
21. An icy, dusty object that orbits the Sun and develops a tail when it nears the Sun.
22. The 23.5-degree slant of Earth's axis, which is the main cause of the seasons.
23. A celestial body that orbits the Sun and is nearly round, but hasn't cleared its orbital path (e.g., Pluto).
24. A large planet composed mainly of hydrogen and helium, like Jupiter or Saturn.
25. Data collected using one or more of the five senses or with the help of scientific tools.
28. Occurs twice a year when the Sun crosses the celestial equator, meaning day and night are of nearly equal length.
29. A moon phase where less than half of the Moon is illuminated.

1. Scientific data or facts gathered through observation or experimentation to support a conclusion.
3. The imaginary line that passes through Earth's center from the North Pole to the South Pole.
5. A unit of distance equal to the average distance between Earth and the Sun (AU).
6. The four natural divisions of the year caused by the Earth's tilt and revolution around the Sun.
7. The periodic rise and fall of sea level, mainly caused by the gravitational pull of the Moon and Sun.
9. A term for the inner, rocky planets: Mercury, Venus, Earth, and Mars.
11. A tide that occurs during the full and new moon, producing the greatest difference between high and low water.
14. A well-substantiated explanation of some aspect of the natural world, based on a body of facts.
15. A testable prediction or educated guess based on observations and prior knowledge.
16. A tide that occurs during the first and third quarter moon, producing the smallest difference between high and low water.
19. The curved path of a celestial body or spacecraft around a star, planet, or moon.
20. Occurs twice a year when the Sun reaches its highest or lowest point in the sky, marking the longest and shortest days.
26. Occurs when one celestial body, like the Moon, blocks the light from another, like the Sun.
27. The motion of one body around another, like the Earth orbiting the Sun.