Motions Of The Earth (Basic)

Rotation

Day And Night

Rotation is the movement of the Earth on its own axis from west to east. It takes approximately 24 hours to complete one full rotation.

This rotation causes the phenomenon of day and night. The side of the Earth facing the Sun experiences day, while the opposite side remains in darkness, experiencing night.

The Earth's axis is tilted at an angle of 66½° with its orbital plane, which plays a crucial role in varying the length of day and night throughout the year.

Revolution

Seasons

Revolution refers to the Earth's movement around the Sun in an elliptical orbit. It takes approximately 365¼ days (1 year) to complete one revolution.

The revolution of the Earth, combined with the tilt of its axis, causes the change of seasons — summer, winter, spring, and autumn.

Summer Solstice

The Summer Solstice occurs around 21st June when the Northern Hemisphere is tilted towards the Sun. On this day:

• The Sun shines directly over the Tropic of Cancer (23½° N).
• The Northern Hemisphere experiences the longest day and shortest night.
• It marks the beginning of summer in the Northern Hemisphere.

Winter Solstice

The Winter Solstice occurs around 22nd December when the Southern Hemisphere is tilted towards the Sun. On this day:

• The Sun shines directly over the Tropic of Capricorn (23½° S).
• The Northern Hemisphere experiences the shortest day and longest night.
• It marks the beginning of winter in the Northern Hemisphere.

Equinoxes

Equinox means “equal night.” On these two days, the Sun shines directly over the Equator (0°), and day and night are approximately equal in length all over the world.

• Spring or Vernal Equinox: Around 21st March — Marks the beginning of spring in the Northern Hemisphere.
• Autumnal Equinox: Around 23rd September — Marks the beginning of autumn in the Northern Hemisphere.