What is The year and the seasons? — Physics

Definition 18.6 Primary & Middle School Physics · Chapter 18 — The Sun in the Sky: Days and Seasons

While the Earth spins once a day, it also travels along a huge journey around the Sun — one full lap takes a year, about $365$ days. Along the lap, the Sun’s road through our sky slowly rises and falls, and we pass through the four seasons: spring, summer, autumn, winter — then spring again, lap after lap.

One lap of the Earth around the Sun — one year, four seasons. Why the low road in winter and the high road in summer? That secret is kept for a later chapter on the Sun–Earth–Moon family.

Examples

Example 18.7 (The four quarters)

Summer: high Sun, long days, short midday shadows. Winter: low Sun, short days, long midday shadows. Spring and autumn sit between — and in each of them comes one special day when daytime and night last equally long. Farmers, sailors and builders of old learned to read this calendar straight from the sky.

Example 18.3 (Reading the season from a shadow)

The length of the midday shadow changes with the season: in summer, with the Sun nearly overhead, the midday shadow of a post is a short stump; in winter, with the Sun hanging low, the same post throws a long midday shadow. Mark the tip of the midday shadow on the ground once a month, and the marks will crawl back and forth through the year like a slow pendulum.

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