| A | B |
|---|
| asthenosphere | the partially melted layer of the mantel that underlines the lithosphere. |
| autumnal equinox | start of fall in the northern hemisophere, occuring on or about semptermber 22nd each year when the noon sun is directly over the equater; one of the two days each year (with the vernal equinox) when day and night are of equal length in both hemospheres. |
| crust | the very thin outer layer of the earth above the mantal, composed of the regid layer of lighter rocks that can extend 65 kilomiters at its deepest point. |
| geology | study of earth's surface and interior |
| inner core | the solid innermost layer of the earth, composed of iron and nickel under extremely high pressure and tempurture. |
| lithosphere | the outer shell of the earth consisting of the crust and upper most portion of the mantel. |
| international dateline | teh imaginary line placed at roughly 180 degrees longitued where the new callender day begins, moving east to west. |
| magnetic field | an area in which the motion of charged particles creates a magnetic force, sch as the field of magnetic force generated b the movement of fluid in the earth's outer core. |
| mantle | the thickest of earth's layers located between the outer core and earhts crust, composed mostly of compounds rich in iron,silicon, in magnesium |
| outer core | the layer of earths interior located between the inner core and mantle, composed of iron and nickel in a liquid state. |
| parallax | The apperent shift in one object's posion relative to another caused by a chage in the location of the observer |
| prime meridian | the imaginary line dividing Earth's surface into Eastern and Western Hemispheres, established as zero degrees at Greenwich, England; the starting point for standing time zone |
| revolution | the movemnet of one body around another, such as the Earth in its orbit around the sun |
| rotation | the turning of a body, such as Earth, on its axis |
| standard time zone | areas roughly defined by twenty-four 15 degrees section of longitude, each center on a time meridian that establishes the hour of the day |
| summer solstice | the fist day of summer in the Northern Hemisphere, which occurs on or about June 21 each year when the noon sun appears to reach its most northern point in the sky |
| prime meridian | the imaginary line dividing Earth's surface into Eastern and Western Hemispheres, established as 0 degrees |
| vernal equinox | start of spring in the Northern hemisphere, on or about March 21 (day & night are od equal length in both hemispheres) |
| winter solstice | the first day of winter in the Norhtern Hemisphere, on Dec. 21 each year when the noon sun appears to reach its most southern point in the sky |
| fusion | the combining of the nuclei of lighter elements to form a heavier element |
| plasma | a state of matter consisting of charged particles- positively charged ions and negatively charged electrons |
| photosphere | the visible layer of the sun |
| chromosphere | the inner layer of the sun's atmosphere located above the photosphere |
| corona | the outermost layer of the sun's atmosphere located above the chromosphere |
| sunspot | dark areas on the sun's photosphere that result from variations in the sun's magnetic feild |
| solar wind | a constant stream of electrically charged particles that is blown out from the sun in all directions |
| aurora | a glow in the night sky produced by particles from the solar wind interacting with Earth's magnetic field |
