Which type of astronomical observation is most strongly affected by the growing problem of light pollution in urban areas?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. Deep-sky object observation.
Deep-sky objects (DSOs), such as galaxies, nebulae, and star clusters, are extremely faint and diffuse sources of light. Light pollution creates a pervasive "skyglow" that brightens the background of the night sky, dramatically reducing the contrast between the faint DSO and the sky. This makes it challenging, and often impossible, to detect or image these distant objects, especially in urban and suburban areas.
Other Options Explained:
- Sunspot monitoring: This involves observing the Sun, which is an extremely bright object and is done during the daytime. Therefore, it is completely unaffected by night-time light pollution.
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Planetary transit viewing: This involves observing a planet passing across the face of the Sun (a rare event) or a bright star. Since the target object (planet/star) is very bright and the transit is measured relative to its face, the faint background skyglow has a negligible impact.
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Moon phase tracking: The Moon is the brightest object in the night sky. Its phases are easily visible and tracked even in the most light-polluted cities, as its brightness completely overwhelms any urban skyglow.