(A) Think and tell.
1. On a new moon day, we cannot see the moon even though it is there in the sky. Why is that so?
Ans. i) The earth gets direct light from the sun while the moon gets the reflected sunlight from the earth and is visible to us. ii) On a new moon day the moon does not get any reflected light from the sun, hence cannot be seen even though it is there in the sky.
2. Why do birds return to their nests earlier in winter than in summer?
Ans. The days are longer during summer and shorter in winter. As there is early sunset in winter, there is early darkness. Therefore the birds return to their nests earlier in winter than in summer.
(B) Answer in brief.
1. From where does the earth get light?
Ans. The earth gets its light from the sun.
2. What is the earth shaped like?
Ans. The earth has a shape like that of a large ball.
3. When do we say that it is daytime?
Ans. We say it is daytime when we get sunlight and it is bright.
4. When do we say that it is nighttime?
Ans. We say it is night when we do not get sunlight and it is dark.
1. The spinning of the earth.
Ans. i) The earth moves around the sun, this motion of earth is called revolution. ii) While revolving around the sun the earth also moves around itself about an axis, called the rotation. iii) This motion of rotating around its axis is also called as the spinning of earth.
2. The cycle of day and night.
Ans. i) The earth has two types of motions the rotation around its axis and revolution around the sun. ii) At any time half of the earth faces the sun and has day while other have that do not face the sun has night. iii) Due to the rotation motion of the earth the side facing the light goes towards darkness and the side that had darkness goes towards light. This causes the cycle of day and night.
(D) Fill in the blanks.
1. The whole day has 24 hours.
2. The sun appearing in the sky in the morning is called sunrise .
3. The disappearance of the sun from the sky in the evening is called sunset .
4. From March 22 till 21 June our days become longer and the nights shorter.
(E) True or false?
1. The number of hours in the day and the night on March 22 are equal. True
2. In our part of the earth, on June 21, the day is the longest and the night, shortest. True
3. On September 22, the lengths of the day and the night are unequal. False
4. In our part of the earth, on December 22, the day is the longest and the night, are shorter. False