Important Notes : Earth

The Equatorial radius of the earth is 6378.245km and the Polar radius is 6356.863 km. Thus, the shape of the earth is an oblate ellipsoid.

The age of our planet earth is 4.6billion years

The mean surface temp is 14 degree Celsius approximately.

There are various theories about the creation of the planet out of which the Big bang theory is one of the most important. 

The universe is still expanding and expansion of universe means increase in the space between galaxies 

Rotation of the earth 

• Our planet earth spins on imaginary axis from west to east.
• Because of rotation there is Day and night on our planet earth 
• Earth takes 23 hours, 56 minutes and 4 seconds to complete one rotation.

Revolution of the earth 

• Movement of earth around the sun 
• Change of season occurs on earth due to revolution of the earth 
• It takes 365days, 5hours and 45.5 seconds to complete one revolution 

• The additional 5 hours and 45.5 seconds add up to make a Leap year once in every four years 

Latitudes 

•  Latitude is the angular distance measured north and south of the equator
• A line joining places of equal latitude is called Parallel of latitude
• The Equator is the greatest circle possible on the surface of the earth. It is simply referred to as great circle
• All latitudes are parallel to each other and each degree covers a distance of 111km
• The Tropic of Cancer passes through eight states in India. They are Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura, and Mizoram

Longitude

• Longitude is the angular distance measured east and west of the prime meridian
• Meridians of longitude are of equal length , they converge at poles
• Prime Meridian passes through Royal Observatory in Greenwich, London 
• 180 degree is the International date line
• Indian Standard Time is considered at 82.5 degree longitude which is 5hours and 30 minutes ahead. 
• It passes through five states namely, Uttar Pradesh, Madhya Pradesh, Odisha, Chhattisgarh, Andhra Pradesh

Note -Grid is a network of lines crossing each other horizontally and vertically Intersecting at right angles 

Seasons

• Solstice is the time when the sun is at the greatest distance from the equator, and sun rays are vertical at Tropic.
• Equinoxes is when neither of the two hemispheres is tilted, duration of day and night is equal during equinoxes 
• The origin may be tracked to Latin word equus which means equal, and nox which mean night
• Norway is called the land of midnight sun

Q. Which one of the following is known as the land of midnight sun?

a. Norway 

b. Switzerland 

c. New York 

d. India 

Ans -a

Q. In the interior of the earth

a. The temperature falls with increasing depth

b. The pressure falls with increasing depth

c. The temperature rises with increasing depth

d. The temperature and pressure falls with increasing depth

Ans-c

Q. degree of latitude represents how many kilometers?

a. 321

b. 211

c. 111

d. 91

Ans-c

Q. How can the International Date Line are explained in simple terms.

a. It is the equator

b. 180-degree longitude

c. 90 degree east longitude

d. Zero degrees longitude 

Ans-b

Q. Which one of the following is known as the Great circle?

a. Tropic of cancer 

b. Tropic of Capricorn

c. Equator

d. Arctic circle

Ans-c

Q. Indian standard time passes through?

a. 23.5-degree longitude 

b. 82-degree longitude 

c. 82.5-degree longitude 

d. 66.5-degree longitude 

Ans-c

Q. The mean surface temp on the earth’s surface is approximately?

a. 18 degree Celsius 

b. 22 degree Celsius 

c. 14 degree Celsius 

d. 25 degree Celsius 

Ans-c

Q. day and night occurs due to?

a. Rotation of the earth

b. Revolution of the earth

c. Both a and b 

d. Axis of rotation 

Ans-a

Q. change of seasons occurs due to?

a. Rotation of the earth

b. Revolution of the earth

c. Sunrays on Norway

d. Axis of rotation 

Ans-b

Q. Tropic of cancer passes through how many states in India?

a. 8

b. 7

c. 6

d. 5

Ans-a