2. The Sun, the Moon and the Earth
Complete textbook exercise solutions, activities, moon phases, and eclipses. Maharashtra State Board (Balbharati).
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Exercises
(1) The moon revolves around the sun.
Wrong.
Correct statement: The moon revolves around the earth.
(2) On a full moon day, the moon, the sun and the earth are positioned in this sequence.
Wrong.
Correct statement: On a full moon day, the sun, the earth and the moon are positioned in this sequence.
(3) The revolutionary orbits of the earth and the moon are in the same plane.
Wrong.
Correct statement: The revolutionary orbits of the earth and the moon are not in the same plane. The moon's orbit makes an angle of about 5° with the earth's orbit.
(4) In one revolution of the moon, its orbit intersects the earth's orbit only once.
Wrong.
Correct statement: In one revolution of the moon, its orbit intersects the earth's orbit twice.
(5) It is alright to observe a solar eclipse without protecting the eyes.
Wrong.
Correct statement: It is not alright to observe a solar eclipse without protecting the eyes. One must use dark glasses or special goggles to avoid harm from intense sunlight.
(6) An annular solar eclipse occurs when the moon is in the perigee position.
Wrong.
Correct statement: An annular solar eclipse occurs when the moon is in the apogee position.
(1) Solar eclipse
- (a) Moon – Earth – Sun
- ✔ (b) Earth – Moon – Sun
- (c) Earth – Sun – Moon
Reason: A solar eclipse occurs when the moon is between the earth and the sun, and all three are in one straight line in the same plane.
(2) The shape of sun disc at the time of annular solar eclipse.
- (a) Completely dark disc
- ✔ (b) Dark disc with a bright ring around it
- (c) Partially dark disc
Reason: During an annular solar eclipse, only the illuminated edge of the sun disc is seen in the form of a ring.
(3) Apogee position of the moon.
- ✔ (a) Moon at its farthest position from Earth
- (b) Moon closer to Earth
- (c) Moon's angle of revolution
Reason: Apogee is the position where the moon is at its farthest distance from the earth.
| Details | Lunar Eclipse | Solar Eclipse |
|---|---|---|
| Phase of the moon | Full moon day | New moon day |
| Sequence | Moon-Earth-Sun | Earth-Moon-Sun |
| Type of eclipse | Total and Partial | Total, Partial, and Annular |
| Maximum duration of total eclipse | 107 minutes | 7 minutes and 20 seconds (440 seconds) |
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(1) Total and partial solar eclipse.
Students should refer to Figure 2.5 on page 5 of the textbook. The diagram should show the Sun, Moon, and Earth in a straight line, with the Moon's dark inner shadow (umbra) creating a total solar eclipse on a small portion of the Earth, and the lighter outer shadow (penumbra) creating a partial solar eclipse.
(2) Total and partial lunar eclipse.
Students should refer to Figure 2.8 on page 6 of the textbook. The diagram should show the Sun, Earth, and Moon in a straight line. If the Moon is completely within the Earth's dark shadow, label it 'Total lunar eclipse'. If only a part is in the shadow, label it 'Partial lunar eclipse'.
(1) Why do the sun, the moon and the earth not lie in one and the same line on every full moon and new moon day?
The orbital path of the earth and that of the moon are not in the same plane. The moon's revolutionary orbit makes an angle of about 5° with that of the earth. Because of this angle, they do not fall in one straight line in the same plane on every new moon or full moon day.
(2) When total solar eclipse occurs why is partial eclipse also seen from the earth?
When the moon is between the sun and the earth, its shadow falls on the earth. This shadow has two parts: a central darker portion and a lighter periphery. In the area of the dark shadow, a total solar eclipse is seen. At the same time, in the surrounding area where the shadow is lighter, the sun disc appears partially covered, resulting in a partial solar eclipse being seen.
(3) Suggest measures that can be taken to eradicate the superstitions related to the eclipses.
We can spread awareness that eclipses are purely astronomical events resulting from specific positions of the sun, earth, and moon, and have no 'auspicious' or 'inauspicious' effects. Schools and science clubs can organize safe eclipse-viewing events using protective gear to encourage scientific curiosity rather than fear.
(4) What precautions should we take while observing a solar eclipse?
While observing a solar eclipse, it is necessary to view the sun disc through dark glasses or special goggles made specifically for that purpose. We should never look at the sun directly with naked eyes, as the intense light can be harmful and damage our vision.
(5) What types of solar eclipses will occur in perigee condition?
In a perigee condition, the moon is at its closest distance to the earth. During this time, its dark shadow can reach the earth's surface. Therefore, a Total Solar Eclipse and a Partial Solar Eclipse can occur in this condition.