🔍 Key Concepts

• Apparent magnitude scale used in astronomy and navigation • Relationship between magnitude number and brightness (smaller number = brighter star) • Visibility of stars to the unaided human eye at sea under good conditions

💭 Think About

• Think about which range of star brightness is most useful for practical sextant observations from a vessel at sea. • Ask yourself: up to what magnitude can most navigators reliably see and measure stars without optical aids? • Consider how including very faint stars would affect the usefulness and size of the Star List in the Nautical Almanac.

✅ Before You Answer

• Recall that lower magnitude numbers mean brighter stars on the apparent magnitude scale. • Verify typical limiting magnitude for naked-eye visibility on a dark, clear night at sea. • Consider which choice best matches the faintest stars that are still practically useful for routine celestial navigation.