Welcome to practical physicsPracticle physics - practical activities designed for use in the classroom with 11 to 19 year olds

The motion of the Sun

At noon the Sun is always due south in the northern hemisphere and due north in the southern hemisphere. It appears to make one revolution from noon to noon (except for some minor deviations which are connected with the changing speeds of the Earth’s orbital motion round the Sun). 

Relationship between apparent daily patterns of the Sun and annual orbit of Sun, shown for northern hemisphere

The stars appear to make about 1° more than one revolution (360°), so the Sun does not move quite so fast. Like the Moon, the Sun lags behind the movement of the star pattern. But you cannot see it doing this because the stars are not visible during the daytime.

The Sun's apparent lagging path

The lagging motion of the Moon carries it right round the ecliptic circle through the star pattern in a month. But the lagging motion of the Sun is slower: 1° in a day, all the way round in a year. 

The Zodiac is a belt of the celestial path tilted 23½° from the Equator. The Sun’s yearly path (the ecliptic) runs along the middle line of this belt. The paths of the Moon and planets lie within this belt, which is only 15° wide.

The Zodiac was divided into twelve sections


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