Planetary 3-hourly index of geomagnetic activity - provisional data
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Seasons The earth's position in relation to the sun is always changing. The earth spins around its axis, an imaginary line that runs between the north and south poles. One complete spin takes 24 hours, and at any moment, half of the earth is lit and warm (day), while the other half faces away from the sun (night). While it spins the earth also moves around the sun in a circle, called an orbit, and the orbit takes one year to complete. As the earth moves and spins it is tilted in one direction at an angle of 23 degrees. It stays tilted all the time as it orbits the sun, so that each area of earth receives different amounts of the sun's energy at different times of the year. This is why we have seasons. |