Beyond Earth — NCERT Solutions

Given: An artist's representation of the Solar System (Fig. 12.12 — image not fully visible, but we can provide the correct order).

Concept: The eight planets are arranged in order of increasing distance from the Sun.

Correct order of planets from the Sun (nearest to farthest):

$$\text{Sun} \rightarrow \text{Mercury} \rightarrow \text{Venus} \rightarrow \text{Earth} \rightarrow \text{Mars} \rightarrow \text{Jupiter} \rightarrow \text{Saturn} \rightarrow \text{Uranus} \rightarrow \text{Neptune}$$

Answer: If the order in the figure does not match the above sequence, it is incorrect. The correct order from the Sun outward is:

1. Mercury
2. Venus
3. Earth
4. Mars
5. Jupiter
6. Saturn
7. Uranus
8. Neptune

Check the figure against this order and correct any planet that is placed out of sequence.

Note: Fig. 12.13 is an image that requires direct observation and drawing. The solution below describes what to do and what to look for.

Steps to identify and draw:

Big Dipper:

• Look for a group of 7 bright stars arranged in the shape of a large ladle or dipper (like a cup with a long handle).
• 4 stars form the rectangular 'cup' and 3 stars form the curved 'handle'.
• Draw lines connecting these 7 stars and label the pattern 'Big Dipper'.

Little Dipper:

• The Little Dipper is a smaller, fainter group of 7 stars also shaped like a ladle.
• It appears near the Big Dipper but is smaller and less bright.
• Draw lines connecting these stars and label the pattern 'Little Dipper'.

Pole Star (Polaris):

• The Pole Star is located at the tip of the handle of the Little Dipper.
• To locate it from the Big Dipper: draw an imaginary line through the two stars at the outer edge of the Big Dipper's cup and extend it about 5 times the distance between those two stars — this leads to the Pole Star.
• Label this star as 'Pole Star (Polaris)'.

Conclusion: Complete the drawing in Fig. 12.13 by connecting the stars with lines as described above and adding the labels.

Note: Fig. 12.14 is an image that requires direct observation and drawing. The solution below describes what to do.

Steps to identify and draw Orion:

Orion:

• Look for three bright stars in a short, straight line close together near the middle of the figure — these represent Orion's Belt, which is the easiest feature to identify.
• Around these three stars, identify more stars that form the outline of a hunter:
• Two bright stars above the belt (shoulders)
• Two stars below the belt (feet/knees)
• Some stars forming the head
• Draw lines connecting all these stars to form the shape of Orion and label it 'Orion'.

Sirius:

• Once Orion is identified, draw an imaginary straight line through the three belt stars of Orion and extend it towards the east (left side).
• The very bright star that this line points to is Sirius.
• Label this bright star as 'Sirius'.

Conclusion: Complete the drawing in Fig. 12.14 by connecting the stars of Orion with lines and labelling Sirius as directed.

Given: Stars fade at dawn, appear at dusk, and are not visible during the day.

Explanation:

Stars are present in the sky both during the day and at night — they do not disappear. However, we cannot see them during the day because of the following reason:

• The Sun is a very bright star very close to us. During the day, sunlight is scattered in all directions by the Earth's atmosphere, making the entire sky very bright (blue sky).
• This scattered sunlight is so much brighter than the faint light coming from distant stars that the light from stars gets completely overwhelmed and our eyes cannot detect it.
• At dusk, the Sun sets below the horizon and the sky gradually becomes darker. As the sky darkens, the light from stars becomes visible one by one.
• At dawn, as the Sun rises, the sky brightens again and the stars fade away one by one.

Conclusion: We do not see stars during the day not because they are absent, but because the brightness of the daytime sky (due to scattered sunlight) makes the stars' light invisible to our eyes.

This is an observation-based activity. Below is the expected observation and explanation.

Observation:
When you observe the Big Dipper at different times during the night (e.g., at 9:00 pm, 11:00 pm, 1:00 am, and 3:00 am), you will notice that:

• Yes, the Big Dipper appears to move across the sky over the course of the night.
• It appears to rotate or revolve around the Pole Star in an anti-clockwise direction.
• The Pole Star, however, remains nearly fixed in the same position throughout the night.

Reason: The Earth rotates on its own axis from west to east. Due to this rotation, all stars (except the Pole Star, which lies almost exactly on the Earth's axis of rotation extended) appear to move across the sky from east to west.

Rough Sketch Description:
Draw the Pole Star at the centre. Around it, draw the Big Dipper in four different positions:

• Position 1 (9:00 pm): Big Dipper to the right of Pole Star
• Position 2 (11:00 pm): Big Dipper slightly higher/rotated
• Position 3 (1:00 am): Big Dipper above the Pole Star
• Position 4 (3:00 am): Big Dipper to the left/further rotated

Label each position with the time of observation. Draw a curved arrow around the Pole Star to show the direction of apparent movement (anti-clockwise).

Conclusion: The Big Dipper appears to move (rotate around the Pole Star) due to the rotation of the Earth, while the Pole Star stays nearly stationary.

This is a creative writing activity. Below is a sample poem.

A Poem: The Night Sky

When the golden Sun bids the day goodbye,
A thousand tiny lamps light up the sky.
The Moon glows softly, silver and bright,
Guiding the world through the quiet night.

Orion stands tall with his belt of three,
And the Big Dipper pours stars for you and me.
The Pole Star stands still, steady and true,
Pointing the North in the dark navy blue.

Planets wander slowly, one by one,
All in their orbits around the Sun.
Comets streak past like a fiery tail,
Asteroids tumble along their trail.

The Milky Way stretches, a river of light,
A galaxy of wonders on a clear winter night.
Look up, look up, at the sky above —
The universe is filled with mystery and love.

(Students are encouraged to write their own original poem or story based on their personal observations and imagination.)