The Earth

1.2

State the approximate diameter of Earth

1.3

State that Earth’s orbit is not quite circular but is elliptical

1.4

Explain the terms perihelion and aphelion

1.5

State that Earth’s axis is tilted, and explain the terms equator, ecliptic

1.6

Explain the terms latitude, longitude, pole, meridian, zenith and horizon

1.7

State that the Earth-Sun distance is one astronomical unit, assuming Earth has a circular orbit

1.8

Explain that the astronomical unit is, more accurately, the mean Earth-Sun distance

1.9

Describe Earth’s unique features, water surface, oxygen-rich atmosphere, supports life

1.10

Describe the effect of Sun and Moon on Earth’s tides

1.11

Explain the scattering in the Earth’s atmosphere and why the sky is blue

1.12

Describe benefits and drawbacks of the atmosphere, to mankind and to astronomers

 Describe problems of chemical pollution and light pollution, and the siting of an observatory

1.16

Explain that apparent East-West motion of Sun and Moon implies West-East rotation of Earth

1.17

Explain the need for time zones due to the rotation of Earth

1.18

State the astronomical significance of a day and a year

1.19

Distinguish between a solar day and a sidereal day, and explain the four minute difference

1.20

Describe how the Sun moves in the ecliptic, and explain the terms equinox and solstice

1.21

Explain the connection between Earth’s axial tilt and the orbital movement of the season’s

1.22

Explain the astronomical significance of observations made with a shadow stick

1.23

Construct diagrams to show the variation in daylight length in a year given appropriate data

1.24

Explain the graduations of horizontal and vertical sundials, and the angle of the gnomon

1.25

Explain the seasonal variations in the rising and setting of the Sun through the year

1.26

Explain the terms mean sun and mean solar time

1.27

Explain the equation of time and perform simple calculations