| A | B |
|---|
| seismic wave | vibration that travels through Earth |
| crust | outermost layer of the solid earth |
| mantle | layer of rock below the crust of the earth |
| core | center of Earth |
| lithosphere | rigid outer shell of Earth consisting of crust & the upper mantle |
| asthenosphere | layer of the mantle beneath the lithosphere that consists of slowly flowing solid rock |
| Moho | Mohorovicic discontinuity; boundary between Earth's crust & mantle |
| shadow zone | location on Earth's surface where no seismic waves or where only P waves can be detected |
| S waves | secondary wave; wave generated by earthquake & the second to be recorded by seismograph |
| P waves | primary wave; fastest wave generated by an earthquake & the first to be recorded by seismograph |
| rotation | spinning of a planet on its axis |
| revolution | movement of a planet around the sun |
| perihelion | point in the orbit of a planet in which it is closest to the sun |
| aphelion | point in the orbit of a planet in which it is farthest from the sun |
| solstice | when sun appears to stop in its northern or southern track in the sky |
| equinox | day when the hours of daylight & darkness are equal everywhere on Earth |
| satellite | object in orbit around a body with a larger mass |
| geosynchronous orbit | orbit directly above the Earth's equator & moving in the direction of Earth's rotation |
| polar orbit | orbit that passes over Earth's North & South Poles |
| latitude | angular distance north or south of the equator |
| parallels | any imaginary circle that runs east & west around Earth parallel to the equator |
| longitude | angular distance east or west of the prime meridian |
| meridians | imaginary semicircle on Earth that runs north & south from pole to pole |
| magnetic declination | angle between the direction of Earth's geographic pole & the direction a compass needle points |
| map projection | flat map that represents a 3D curved surface |
| mercator | map projection in which the meridians appear as straight, parallel evenly spaced lines which forma grid with the parallels |
| conic | map projection made so that the axis of the cone aligns with the axis of the globe |
| gnomonic (polar) | map projection in which the parallels appear as unevenly space concentric circles & meridians appear as straight lines radiating out from a central point |
| legend | list of map symbols & their meanings |
| scale | relationship between distance shown on a map & actual distance |
| topographic map | map that shows the surface features of Earth |
| elevation | height above sea level |
| contour lines | line on a map connecting points with the same elevation |
| relief | difference in elevation between the highest & lowest points of an area |
| contour interval | difference in elevation between one contour line & the next |
| index contour | every fifth contour line on a topographic map that is printed dark for reference |
