SIGNIFICANCE OF THE EARTH'S AXIS AND REVOLUTION

What is the angle of the Earth's axis?

The Earth's axis is tilted at 23.5° from vertical (or 66.5° from the horizontal plane of its orbit).

What is the difference between rotation and revolution?

Rotation is the spinning of the Earth on its own axis — it causes day and night. Revolution is the movement of the Earth around the Sun — it takes 365.25 days and causes seasons.

What causes seasons?

The tilt of the Earth's axis (23.5°) as it revolves around the Sun in an elliptical orbit. When a hemisphere tilts toward the Sun it experiences summer; when it tilts away, it experiences winter .

What is the Tropic of Cancer and Tropic of Capricorn?

The Tropic of Cancer (23.5°N) is where the sun is directly overhead on 21 June (Northern Hemisphere summer solstice). The Tropic of Capricorn (23.5°S) is where the sun is directly overhead on 21 December (Southern Hemisphere summer solstice).

What is the Summer Solstice in the Southern Hemisphere?

21 December — the Southern Hemisphere is tilted toward the Sun. Days are longest, nights are shortest, and it is summer in South Africa.

What is the Winter Solstice in the Southern Hemisphere?

21 June — the Southern Hemisphere is tilted away from the Sun. Days are shortest, nights are longest, and it is winter in South Africa.

What is an Equinox and when does it occur?

When the Sun is directly over the equator and all places on Earth have equal 12-hour days and 12-hour nights. It occurs on 21 March and 23 September

What is perihelion and aphelion?

Perihelion is when the Earth is closest to the Sun during its elliptical orbit. Aphelion is when the Earth is furthest from the Sun.

How does the Earth's axis affect the unequal length of day and night?

The tilt means that as the Earth revolves, one hemisphere receives more direct sunlight with longer days, while the other receives less with shorter days — causing unequal heating.