Theory question 303
The Earth and Solar System(a) List the four seasons of the year. (b) Outline two differences between standard time and local time. (c) With the aid of a diagram, describe the formation of solar eclipse.
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(a) Spring; summer; autumn; winter.
(b) Local time is the time of a place based on the sun's position on its own meridian (noon when the sun is highest), standard time is the time adopted for a whole country or time zone; local time changes by 4 minutes for every degree of longitude, standard time changes in whole hours (15°); local time differs from place to place within a country, standard time is the same throughout a zone.
(c) Diagram: sun, moon and earth in a straight line with the moon in the middle, umbra and penumbra on the earth. The moon revolves round the earth; at new moon it sometimes passes directly between the sun and the earth; it blocks the sun's light and casts a shadow on part of the earth; places in the umbra see a total eclipse, places in the penumbra a partial eclipse; it lasts only a few minutes.
The moon is in the middle for a solar eclipse.