Are the stars visible at 7 pm still visible at 11 pm in their original position? Why is this so?
The correct answer and explanation is:
Correct Answer:
No, the stars visible at 7 PM are not in the same position at 11 PM.
Explanation (300 words):
Stars appear to move across the night sky over time due to Earth’s rotation on its axis. This rotation causes the entire celestial sphere (the sky as we see it) to shift from east to west. Earth completes one full rotation approximately every 24 hours, which makes it look like the stars move in arcs across the sky.
If you observe the stars at 7 PM and then again at 11 PM, you will notice that the stars have shifted westward by about 60 degrees. This is because the Earth rotates about 15 degrees every hour (360 degrees ÷ 24 hours = 15 degrees/hour). So in four hours, the stars move 15 × 4 = 60 degrees across the sky.
This westward movement means that stars that were rising in the east at 7 PM will be higher in the sky or possibly overhead by 11 PM. Likewise, stars that were overhead at 7 PM will be heading toward the western horizon by 11 PM and may even set if enough time passes. Additionally, stars that weren’t visible at 7 PM may rise by 11 PM.
This motion is consistent every night and is not caused by the stars themselves moving, but rather by Earth turning beneath the sky. That’s why constellations like Orion or the Big Dipper change position in the sky over hours or appear in different parts of the sky as the seasons change.
In summary, the stars you see at 7 PM will not be in their original position at 11 PM because of the Earth’s rotation, which gives the illusion that the stars are moving across the sky.