Theory question 303
The Earth and Solar System(a) Explain the following terms: (i) rotation of the earth; (ii) revolution of the earth; (iii) equinox. (b) Outline three effects of the revolution of the earth.
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(a)(i) Rotation: the spinning of the earth on its axis from west to east, once in 24 hours.
(ii) Revolution: the movement of the earth round the sun in its elliptical orbit, once in about 365¼ days.
(iii) Equinox: the time (about 21 March and 23 September) when the sun is overhead at the Equator and day and night are equal everywhere.
(b) Seasons; varying lengths of day and night through the year; apparent movement of the overhead sun between the tropics; changing altitude of the midday sun; leap year every four years; perihelion and aphelion; the equinoxes and solstices.
Three effects of revolution, not of rotation.