Textbook Solutions: Rotation and Revolution | Footprints Class 6: Book Solutions, Notes & Worksheets PDF Download

I.  Tick (✔)  the correct option.

1. 
Ans: (b)
Rotation refers to the Earth's spinning or turning on its axis.

2.
Ans: (b)
The Earth's axis is inclined at an angle of 23 (1/2°) from a line perpendicular to the plane of its orbit around the Sun.

3.
Ans: (a)
The circle of illumination is the boundary that separates the illuminated part of the Earth from the dark part.

4.
Ans: (b)
Perihelion is the point in Earth's orbit where it is closest to the Sun.

5.
Ans: (b)
During the summer solstice, the North Pole is tilted towards the Sun, and the Sun's rays fall directly on the Tropic of Cancer.

6.
Ans: (a)
In June, the Northern Hemisphere experiences longer nights because the North Pole is tilted away from the Sun.

7. 
Ans: (c)
During winter solstice, the South Pole is tilted towards the Sun, and the Sun's rays are vertical over the Tropic of Capricorn.

8.
Ans: (b)
21 June is the summer solstice, which is the longest day in the Northern Hemisphere.

9.
Ans: (c)
Equinox comes from Latin and means 'equal nights', referring to the time of the year when day and night are approximately equal in length.

10.
Ans: (b)
This statement is false. March and April are the autumn months for the Southern Hemisphere.

II. State whether the following statements are true or false. 

1. 
Ans: False

2.
Ans: False

3.
Ans: True

4.
Ans: True

5.
Ans: True

III. Answer the following questions in brief.

1. 
Ans: The Sun seems to rise in the east and set in the west due to the Earth's rotation from west to east on its axis.

2.
Ans: Day and night are caused by the Earth's rotation. When a specific part of the Earth faces the Sun, it experiences day, and when it turns away from the Sun, it experiences night.

3.
Ans: The shape of the Earth's orbit around the Sun is an elongated ellipse.

4.
Ans: A leap year is a year that has an extra day, making a total of 366 days. Leap years occur every four years to account for the extra 0.25 days in the Earth's orbit around the Sun.

5.
Ans: An equinox is a point in time when the day and night are approximately of equal duration. There are two equinoxes in a year.

IV. Answer the following questions in detail. 

1.
Ans: The circle of illumination is an imaginary line that separates the illuminated part of the Earth (experiencing daylight) from the dark part (experiencing night). It is a circle that marks the boundary between day and night. To illustrate this concept, draw a circle representing the Earth. Place an arrow to indicate the direction of the Sun's light. Half of the circle facing the Sun will be illuminated (day), while the other half away from the Sun will be in darkness (night).

2.
Ans: An extra day is added to a year after every four years to account for the additional 0.25 days that accumulate over a four-year period. This is because it takes about 365.25 days for the Earth to complete one orbit around the Sun. By adding an extra day in a leap year, we balance out the discrepancy and keep our calendar year synchronized with the astronomical year.

3.
Ans: Seasons are caused by two main factors: the revolution of the Earth around the Sun and the tilt of the Earth's axis. The tilt of the Earth's axis results in different angles at which sunlight reaches different parts of the Earth at different times of the year, creating variations in temperature and weather conditions, which we experience as different seasons.

4.
Ans: It is summer in the Northern Hemisphere in June because during that time, the North Pole is tilted towards the Sun. This means that the Northern Hemisphere receives more direct sunlight, resulting in warmer temperatures and longer days.

5.
Ans: The summer solstice occurs around 21 June when the North Pole is tilted towards the Sun, resulting in the longest day of the year in the Northern Hemisphere. In contrast, the winter solstice occurs around 22 December when the South Pole is tilted towards the Sun, resulting in the shortest day of the year in the Northern Hemisphere.