Motions of the Earth

Question 1

Name the two primary motions of the Earth.

Answer 1

Rotation & Revolution

Question 2

Define Rotation

Answer 2

Rotation is the turning around of the Earth on its axis.

Question 3

Define Revolution

Answer 3

Revolution is the movement of the Earth around the Sun.

Question 4

Define Axis

Answer 4

Axis is the imaginary line passing through the center of the Earth on which the Earth Rotates.

Question 5

How does the tilted axis of the Earth affect the length of days and night of the Earth?

Answer 5

If it was not tilted, All places would experience 12 hours of day & 12 hrs of night.

Question 6

Define Circle of Illumination

Answer 6

It is the imaginary line which demarcates area of light from area of darkness

Question 7

Days and nights vary the least at the ___________ and most at the ___________.

Answer 7

Equator, Poles

Question 8

Speed of Earth’s Rotation at equator

Answer 8

1667 kmph

Question 9

Speed of Earth’s Rotation at the Pole

Answer 9

0

Question 10

Speed of Earth’s Rotation at 40 degrees north

Answer 10

1275kmph

Question 11

Effects of speed of rotation on Earth

Answer 11

1. Affects the shape. A phenomena called the equatorial bulge takes place due to the centrifugal force exerted by rotation of Earth.
2. Affects general circulation of the atmosphere. Moving air is deflected to right in northern hemisphere and to the left in the Southern atmosphere.

Question 12

Effects of Earth’s Rotation

Answer 12

1. Equatorial Bulge
2. East-West movement of the sun and all heavenly bodies
3. Day and night
4. Circulation of air and water: Rotation causes consistent change
5. Tides: Rotation of the Earth results in every meridian coming into the positions of two high tides and two low tides almost every 24 hours

Question 13

Define Coriolis effect

Answer 13

The moving air is deflected to the right in the Northern Hemisphere and left in the Southern Hemisphere.

Question 14

Define Perihelion

Answer 14

On about January 3rd the Earth is closest to the sun. (147 M km)

Question 15

Define Aphelion

Answer 15

On about July 4th the Earth is farthest from the sun. (152 M km)

Question 16

Define Solstice

Answer 16

The time when the midday sun is directly overhead at one of the tropics.

Question 17

Define Equinox

Answer 17

The time when the midday sun is overhead at the Equator.

Question 18

Define Northward apparent migration (Uttarayan)

Answer 18

For six months of the year, the sun appears to be moving north. It begins after 22nd Dec and is completed on June 21st.

Question 19

Define Southward apparent migration (Dakshinayan)

Answer 19

For six months of the year, the sun appears to be moving south. It begins after 21st June and is completed on 22nd Dec.

Question 20

Differentiate between Rotation and Revolution

Answer 20

Rotation
- It is the movement of the Earth around its axis.
- The Earth takes 24 hours to complete one rotation.

Revolution
- It is the movement of the earth around the sun
- The Earth takes 365.25 days to complete one revolution.

Question 21

Differentiate between Aphelion and Perihelion

Answer 21

Perihelion
- On about 3rd January, the Earth is closest to the sun.
- The distance between the earth and the sun is 147.5 million km

Aphelion
- On 4th July the Earth is farthest from the sun
- The distance between the earth and the sun is 152.5 million km

Question 22

Difference between Solstice and Equinox.

Answer 22

Solstice
- The time when the mid-day sun is directly overhead at one of the tropics.
- It takes place on 21st January and 22nd December.

Equinox
- The time when the mid-day sun crosses over the equator.
- It takes place on 21st March and 21st September.

Question 23

GR: We always see the sun rising in the East.

Answer 23

As the Earth rotates from West to East, the eastern part gets lighted first and hence we see the sunrise in the East.

Question 24

GR: The length of day and night equal at all places on the earth on March 21st.

Answer 24

The rays of the sun fall vertical on the equator, so the distribution of light is equal all over the world resulting in duration of day and night equal from pole to pole.

Question 25

GR: Vertical rays are hotter than slanting rays.

Answer 25

Vertical rays are concentrated over a smaller area so they heat up the earth more.

Question 26

GR: Norway is called the land of the Midnight Sun.

Answer 26

A good part of Norway is situated North of the Arctic Circle where the duration of daylight goes on increasing from 24 hrs. to six months poleward.

Question 27

When is
a. Summer Solstice
b. Winter Solstice
c. Spring Equinox
d. Autumn Equinox
e. Aphelion
f. Perihelion

Answer 27

a. 21 June
b. 22 December
c. 21 March
d. 23 September
e. 4 July
f. 3 Jan

Question 28

Effects of Earth’s Revolution

Answer 28

1. Cycle of Seasons
2. Apparent Migration of the Sun resulting in change in altitude of midday sun.
3. Temperature or Heat Zones