| A | B |
|---|
| cycles | changes that repeated over and over again |
| steady trend | change that occurs gradually over time |
| irregular change | change that is unpredictable |
| horizon | the place where the earth and sky seem to meet |
| latitude | lines drawn east and west on a map; measured as north or south of the equator |
| longitude | lines drawn north or south; measured as east or west of the Prime Meredian |
| gnomon | sundial with a center stick |
| axis | the invisible line that runs through the middle of the Earth |
| equator | the imaginary line that circles the Earth halfway between the north and south poles; O degree latitude |
| Prime Meridian | longitudinal line that runs from the north pole to the south pole at 0 degrees |
| International Date Line | the 180 degree meridian that is directly opposite the of the Prime Meredian and is exactly 12 time zones away |
| Standard time zones | zones that divide the Earth equally inton 24 hours; each zone represents 1 hour; all countrues represent these time zones |
| jet lag | common condition that occurs because moving across several time zones causes the body's normal patterns to be disrupted |
| phases | different shapes of the moon; changes in the moon's appearance |
| new moon | occurs when the sun and the moon are on the same side of the earth in a straight line |
| full moon | occurs when the sun and moon are on the opposite sides of the earth in a straight line |
| waxing moon | the moon is getting larger- from new moon to full moon |
| waning moon | the moon is getting smaller- from full moon to new moon |
| blue moon | this occurs once every two to three years during one month that has two full moons; this is the second full moon in that month |
| tides | changes in the ocean's level |
| tidal range | the vertical difference between the high and the low water marks |
| spring tides | occur during the new moon and the full moon; high tides |
| neap tides | occur during the first and last quarter moons; low tides |
| tsunami | tidal wave caused by underwater earthquakes |
| Heliocentric hypothesis | the sun is the center with planets moving around it |
| Geocentric hypothesis | the Earth is the center and other heavenly bodies revolve around it |
| rotation | the Earth moving on its axis |
| revolution | the Earth moving around the sun; the moon moving around the Earth |
| summer solstice | longest day of the year |
| equinox | time when day and night are equal in length |
| parallax displacement | when an object appears to move becasues of a change in position of the observer |
