Why are low altitude sun sights not...

Why are low altitude sun sights not...

Question 1 of 2707066636ee928f7522a1c519b22

Why are low altitude sun sights not generally used?

Question 1 of 27070

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Why are low altitude sun sights not generally used?

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🔍 Key Concepts

• Refraction of light at very low altitudes • How sextant accuracy changes at small angles (near the horizon) • What modern sight reduction tables typically cover for altitude ranges

💭 Think About

• When the observed body (like the sun) is very low, what happens to the light as it passes through more atmosphere? • Is the main concern optical instrument limitations, table limitations, or atmospheric effects? • Which option describes something that can be especially unusual or unreliable when the body is close to the horizon?

✅ Before You Answer

• Compare which options involve instrument limitations versus atmospheric effects. • Ask yourself which condition becomes significantly worse as the altitude approaches the horizon. • Consider what typical sight reduction tables (like HO 229/249) say about minimum usable altitude and why that limit exists.