the point in the Earth's orbit where Earth is farthest away from the Sun.
September 22-23, sun is directly overhead the equator at noon, 12 hour daylight/12 hour night, first day of fall, sun's rays most directly strike the equator, Earth's tilt points at right angle to the sun; the first day of fall in the Northern Hemisphere
an imaginary line that passes through Earth's center and the north and south poles, about which Earth rotates
the center of a planetary body, such as the Earth; the Earth's core is made up of a solid iron inner core, and a liquid iron outer core
the outer solid, rocky layer of the Earth
Daylight Savings Time
setting of cloaks ahead by one hour to provide more daylight at the end of the day during late spring, summer, and early fall.
a circular orbit positioned approximately above Earth's equator and having a period of the same duration and direction as the rotation of the Earth. Communications and weather satellites are usually placed in a geostationary orbit.
the force of attraction between all masses in the universe; the amount of force is dependent on the mass of the objects, and the distance between them
International Date Line
is an imaginary line of longitude generally 180° (degrees) east or west of the Prime Meridian. The International Date Line is where each new day begins.
law of gravitation
the law that states any two bodies attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them
region of space affected by Earth's magnetic field
zone of solid (plastic-like) rock below the Earth's crust
the boundary between the earth's mantle and crust
the point in the Earth's orbit where it comes closest to the Sun.
an orbital path that takes an earth satellite over the poles during each orbit
the slow change in the direction (wobbling) of the rotation axis of a spinning object, caused by some external gravitational influence
the movement of one object around another object
the spinning motion of a planet on its axis
any celestial body orbiting around a planet or star (natural satellite = a moon; artificial satellite = space shuttle)
a vibration that travels through earth carrying the energy released during an earthquake
an area on the Earth's surface where no direct seimic waves from a particular earthquake can be detected.
Standard Time Zone
one of 24 regions of the earth in which noon is set as the time when the sun is highest over the center of the region
on June 21- June 22, it is the longest day and shortest night in the Northern Hemisphere due to the fact that the sun is directly over the Tropic of Cancer; the first day of summer in the Northern Hemisphere
on March 21, it is when there is an equal number of hours of day and night due to the fact that the sun is directly over the equator; the first day of spring in the Northern Hemisphere
on December 21-December 22, the shortest day and longest night of the Northern hemisphere due to the fact that the Sun is directly over the Tropic of Cancer; the first day of winter in the Northern Hemisphere