12. Earth, Moon, and the Sun
Complete solutions to Let Us Enhance Our Learning. CBSE / NCERT Class 7 Science (Curiosity).
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Let Us Enhance Our Learning
- North Pole: 0 hours. It is tilted away from the Sun and stays in the dark half for the whole rotation.
- South Pole: 24 hours. It is tilted towards the Sun and stays in the lit half for the whole rotation.
(i) Stars rise in the East and set in the West.
(ii) Day and night are caused by the Earth’s rotation.
(iii) When the Moon fully covers the Sun from our view, it is called a total solar eclipse.
(i) Lunar eclipse occurs when the Sun comes between the Earth and the Moon. — False
A lunar eclipse occurs when the Earth comes between the Sun and the Moon.
(ii) Sunrise happens earlier in Gujarat than in Jharkhand. — False
The Earth rotates from West to East. Jharkhand is to the east of Gujarat, so sunrise happens earlier in Jharkhand.
(iii) In Chennai, the longest day occurs on the summer solstice. — True
(iv) We should watch the solar eclipse directly with our naked eye. — False
Looking directly at the Sun can permanently damage our eyes.
(v) Seasons occur due to the tilt of Earth’s axis of rotation and its spherical shape. — True
(vi) The Earth’s revolution around the Sun causes day and night. — False
Day and night are caused by the Earth’s rotation.
She will see Orion overhead at nearly 8 pm today, just a few minutes earlier (about 7:56 pm).
The Earth completes one rotation in about 24 hours, so the stars return to almost the same position at the same time each night. Because the Earth also moves a little in its orbit every day, the stars appear about 4 minutes earlier each night.
She will see them rising at midnight on 21 June next year.
The Earth takes about one year to complete one revolution around the Sun. After one year, the Earth is back at the same position in its orbit. So the same stars rise at the same time on the same date.
The reason is the rotation of the Earth.
India and the USA are on nearly opposite sides of the Earth. When India faces the Sun, it has day. At that time, the USA faces away from the Sun, so it has night.
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(iii) Adithya was being careless.
Looking at the Sun directly, even during an eclipse, can seriously damage the eyes. The other three used safe methods.
In a solar eclipse, the Moon is in the middle. In a lunar eclipse, the Earth is in the middle.
The Moon is much closer to the Earth than the Sun. The Sun is about 400 times bigger than the Moon, but it is also about 400 times farther away. So both appear almost the same size in our sky. That is why the Moon can cover the Sun completely.
They should pack summer clothes.
Australia is in the Southern Hemisphere. In December, the Southern Hemisphere is tilted towards the Sun, so it is summer there, while it is winter in India.
- Lunar eclipse: The Earth’s shadow falls on the Moon. The darkened Moon can be seen by everyone on the night side of the Earth. So it is seen from a large part of the Earth.
- Total solar eclipse: The Moon is small, so its dark shadow falls only on a small area of the Earth. Only people in that small area see a total solar eclipse.
There would be no seasons.
- Sunlight would fall on each place in the same way throughout the year.
- Day and night would be nearly equal (about 12 hours each) at almost all places, all through the year.
- Each place would have almost the same weather all year round.
Exploratory Projects
Exploratory Projects are hands-on tasks. Do them with your classmates under the guidance of your teacher, and write your own observations.