| A | B |
|---|
| Aristotle | agreed with Ptolemy that the solar system was earth-centered |
| Ptolemy | believed that the earth was the center of the universe |
| Copernicus | father of modern astronomy |
| Galileo | first to use the telescope |
| Copernicus and Galileo | believed that everything revolved around the sun |
| Moon | about 1/4 the diameter of the Earth |
| Earth | surface is constantly changing |
| Earth has a | protective atmosphere |
| The moon has no | atmosphere |
| sun | about 4.6 billion years old |
| crust | the thinnest layer made up of cool, solide, stone |
| mantle | molten rock |
| outer core | molten iron and nickel |
| inner core | made up of super heated nickel |
| heat and pressure | increase as you get closer to the center of the earth |
| 70% liquid water | also has good gravity and air pressure |
| axis | imaginary line |
| one revolution | one full orbit around the sun |
| equator | always gets direct sunlight |
| solar eclipse | moon between sun and earth |
| lunar eclipse | Earth passes between the sun and the moon |
| crescent moon | moon appears smaller than half of a full moon |
| gibbous moon | moon looks larger than half of a full moon, yet is not a full moon |
| the sun | unevenly heats the earth |
| all planets | held in orbit by gravity |
