🔍 Key Concepts

• Civil twilight and its significance for sight planning • How to determine which planets are above the horizon at a given time and position using the Nautical Almanac • The meaning and sign of meridian angle (t or LHA) for a body east or west of your meridian

💭 Think About

• Based on the date, time, and your DR longitude, is the Sun just after setting or still above the horizon at civil twilight? How does that relate to evening planet visibility? • Using the Nautical Almanac for 20 July, what are the GHA and declinations of Venus, Mars, Jupiter, and Saturn around 1910 zone time, and do their local hour angles put them above the horizon? • For Venus in the evening sky, relative to the Sun’s position, should it typically have an easterly or westerly meridian angle when seen after sunset from this longitude?

✅ Before You Answer

• Verify in the Nautical Almanac which planets are tabulated as being visible for evening twilight at this latitude and date • Check the computed altitude (Hc) for each planet from the DR position to confirm it is above the horizon (altitude > 0°) • Confirm the sign and label of the meridian angle (E or W) for Venus from your DR longitude and the body’s GHA before deciding on any statement about its meridian angle