Celestial Navigation · Planets — Identification
Which characteristic distinguishes the navigational planets (Venus, Mars, Jupiter, Saturn) from stars when observed by eye?
- AThey always appear red
- BThey generally shine with a steady (non-twinkling) light and move relative to the star background over days✓ Correct
- CThey are only visible at midnight
- DThey have measurable parallax like the moon
Explanation
Planets typically shine with a steadier light than the twinkling stars and shift position against the stars over days. The almanac tabulates GHA and declination (with v and d) for the four navigational planets, plus magnitude data for identification.
Authority: Bowditch (Pub. No. 9), the navigational planets; Nautical Almanac
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