Theory question 202
The Earth and Solar SystemUsing relevant sketches, distinguish between (a) solstice and equinox B. the earth's rotation and revolution C. parallels of latitude and meridians of longitude
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Sketch of the earth's positions round the sun on 21 March, 21 June, 23 September and 22 December.
(a) Equinox: sun overhead at the equator; equal day and night everywhere; 21 March and 23 September. Solstice: sun overhead at a tropic (Cancer 21 June, Capricorn 22 December); longest/shortest days; midnight sun or polar night inside the polar circles.
(b) Rotation: earth spins on its axis west to east once in 24 hours; causes day and night, time differences and deflection of winds. Revolution: earth moves round the sun in 365¼ days; with the tilted axis it causes seasons, changing lengths of day and night and the leap year.
(c) Parallels: run east-west, parallel, measure 0-90° N or S, get shorter towards the poles, only the equator is a great circle. Meridians: run north-south from pole to pole, meet at the poles, measure 0-180° E or W of Greenwich, all equal in length, used to find time.
Each pair needs a sketch and clear contrasts.