General Studies 2024 GS Paper I 15 marks 250 words Compulsory Explain

Q15

What are aurora australis and aurora borealis? How are these triggered? (Answer in 250 words) 15

हिंदी में प्रश्न पढ़ें

ऑरोरा ऑस्ट्रेलिस और ऑरोरा बोरियालिस क्या हैं? ये कैसे उत्प्रेरित होते हैं? (उत्तर 250 शब्दों में दीजिए)

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Directive word: Explain

This question asks you to explain. The directive word signals the depth of analysis expected, the structure of your answer, and the weight of evidence you must bring.

See our UPSC directive words guide for a full breakdown of how to respond to each command word.

How this answer will be evaluated

Approach

The question demands a clear explanation of what aurora australis and aurora borealis are, followed by the causal mechanism triggering these phenomena. Structure as: brief definition distinguishing both types → detailed explanation of solar wind-magnetosphere interaction → ionization and excitation process → emission of light → brief mention of best viewing locations.

Key points expected

Definition: Aurora borealis (Northern Lights) occurs in northern hemisphere, aurora australis (Southern Lights) in southern hemisphere; both are natural light displays in polar regions
Solar origin: Coronal mass ejections and solar wind streams of charged particles (electrons and protons) from Sun
Earth's magnetosphere interaction: Charged particles follow magnetic field lines, converging at magnetic poles (auroral zones ~65-75° latitude)
Atmospheric mechanism: Collision with oxygen (green/red at higher altitudes) and nitrogen (blue/purple) causes excitation and photon emission
Geomagnetic storm connection: Intensity linked to Kp index and 11-year solar cycle; recent extreme G5 storm (May 2024) visible in India (Hanle, Ladakh)
Indian relevance: Ladakh's Hanle Dark Sky Sanctuary and Indian Astronomical Observatory track auroral activity; ISRO's Aditya-L1 mission studies solar drivers

Evaluation rubric

Dimension	Weight	Max marks	Excellent	Average	Poor
Demand-directive understanding	20%	3	Clearly distinguishes aurora australis from borealis by hemisphere; addresses both 'what' (definition/visual characteristics) and 'how' (trigger mechanism) components with equal emphasis; no conflation with unrelated phenomena	Defines both terms but treats them as identical except location; covers trigger mechanism superficially or disproportionately focuses on one component	Fails to distinguish between the two types; confuses with other atmospheric phenomena (airglow, noctilucent clouds); misses either definition or causation entirely
Content depth & accuracy	20%	3	Precise scientific explanation: solar wind → magnetosphere → auroral oval → particle precipitation → collisional excitation → specific wavelength emissions; mentions altitude-dependent color variation (O₂ at 100-300km = green, >300km = red; N₂ = blue/purple)	General description of 'solar particles hitting atmosphere' without specifying magnetospheric funneling or excitation chemistry; vague on why colors differ	Incorrect mechanism (e.g., reflection of sunlight, volcanic dust, meteor showers); confuses magnetic poles with geographic poles; no mention of charged particles or magnetic field lines
Structure & flow	20%	3	Logical progression: definitions → solar origin → magnetospheric transport → atmospheric interaction → emission; clear paragraph breaks; 250-word discipline maintained; seamless transition between 'what' and 'how' sections	Adequate organization but abrupt transitions; either definition or mechanism overextended; minor word limit deviation	Disorganized or circular structure; repetitive; severe word limit violation; no clear separation between descriptive and explanatory components
Examples / case-law / data	20%	3	Cites specific viewing locations (Norway's Tromsø, Iceland, Alaska for borealis; Antarctica, New Zealand's Stewart Island, Tasmania for australis); references recent May 2024 G5 geomagnetic storm visible from Ladakh; mentions ISRO's Aditya-L1 or Hanle Observatory	Generic mention of 'polar regions' without specific locations; no contemporary or Indian examples; missing data on solar cycle or storm intensity	No examples whatsoever; incorrect locations (equatorial auroras as normal occurrence); fabricated data or missions
Conclusion & analytical edge	20%	3	Brief forward-looking note on space weather prediction importance, satellite protection, or climate-aurora research links; or connects to India's growing ground-based astronomy infrastructure; concise, value-adding closure	Generic concluding sentence restating definitions; no analytical extension; abrupt ending	Missing conclusion; irrelevant digression into unrelated topics; speculative or pseudoscientific claims about aurora effects

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