9781422283738

Earth , s rotation The Sun does not really circle the Earth every day. It only appears to. The Earth

∆ An unusual sundial at Herstmonceux

Castle, England. The position of the shadow on the circular ring gives the time.

rotates, or spins, in space once a day, moving towards the east. This makes the Sun appear to move towards the west. The solar year

to the calendar year every four years. This is known as a leap year , and the extra day becomes February 29. Among the stars We know that the Earth circles in space around the Sun. But from the Earth it seems that the Sun circles the Earth. The Sun appears to travel through different constellations of stars. It follows the same path each year, called the ecliptic .

The Earth not only spins round in space. It also travels bodily through space in orbit around the Sun. It travels once around the Sun in 365¼ days. This period of time is called the year , or solar year. The calendar used in most countries is based on the solar year. But it is usually 365 days long. To make up for the extra ¼ day of the solar year, an extra day is added

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