REVOLUTION

REVOLUTION

WHAT IS REVOLUTION OF THE EARTH?

• It is motion of the earth around the sun in its orbit.
•  It takes 365¼ days or one year to revolve around the sun.
• The Earth revolves from west to east.

WHY IS REVOLUTION IMPORTANT?

• Revolution causes 4 seasons.

• It is responsible for varied length of day and night time.
• It causes Equinox and solstice.
• Revolution creates perihelion and aphelion situations.

WHAT IS SOLSTICE?

• On 21st June, the northern hemisphere is tilted towards the sun, receive more heat.
• The areas near the poles receive less heat due to the slanting rays.
• The north pole is inclined towards the sun, experience daylight for about six months.
• It is summer in the regions north of the equator.
• The longest day and the shortest night occur on 21st June.
• In the southern hemisphere all conditions are reversed.
• It is winter season there with longer nights. This is called the summer solstice.
• On 22nd December, a larger portion of the southern hemisphere gets light.
• It means summer in the southern hemisphere.
• The reverse happens in the northern hemisphere, called the winter solstice.

WHAT IS EQUINOX?

• On 21st March and September 23rd, sun rays fall direct on the equator.
• At this position, the whole earth experiences equal days and nights.
• This is called an equinox.
• On 23rd September, it is autumn season in the northern and spring in the southern hemisphere.
• The opposite happens on 21st March, spring in the northern and autumn in the southern hemisphere.

WHAT IS PERIHELION AND APHELION?

• Perihelion occurs when the Earth is closest to the Sun.
• Aphelion occurs when the Earth is far from the Sun.