Question 1495Navigation General

70% to pass

The sidereal day begins when the _______________.

A first point of Aries is over the upper branch of the reference meridian
B Sun is over the upper branch of the reference meridian
C first point of Aries is over the lower branch of the reference meridian
D Sun is over the lower branch of the reference meridian
AI Explanation

Correct answer: A) the first point of Aries is over the upper branch of the reference meridian. The sidereal day is defined as the time it takes for the first point of Aries (the vernal equinox) to return to the upper branch of the reference meridian. This is because the first point of Aries is used as a fixed reference point in the sky, rather than the position of the Sun, which is used to define the solar day. The other options are incorrect because they refer to the position of the Sun, not the first point of Aries.

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Official Resources
USCG Navigation Rules (COLREGS) 33 CFR Navigation Rules USCG National Maritime Center
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