默认题库 - 天文航海

单选题

A semidiameter correction is applied to observations of（）.

A. Mars
B. the Moon
C. Jupiter
D. All of the above

单选题

In order for a star to be used for a sight at lower transit，the star must（）.

A. be circumpolar
B. have a declination equal to or greater than your latitude
C. have a GHA of 180°
D. have the SHA equal to or less than the LHA

查看答案

单选题

In the horizon system of coordinates what is equivalent to the equator on the Earth?（）.

A. Prime vertical circle
B. Principal vertical circle
C. Parallels of altitude
D. Horizo

查看答案

单选题

In the horizon system of coordinates what is equivalent to latitude on the Earth?（）.

Altitude
B. Zenith
C. Declination
D. Zenith distance

查看答案

单选题

It is difficult to determine which limb of the Moon is fully illuminated（）.

A. when the Moon is low in the sky at rising or setting
B. at the new Moon phase
C. when taking Moon sights during daylight
D. when the terminator is nearly vertical

查看答案

单选题

On mid-ocean waters，the height of a wind-generated wave is not affected by the（）.

A. water depth exceeding 100 feet
B. fetch
C. wind's velocity
D. duration of the wind

查看答案

单选题

Other than the Sun and Moon，the brightest object in the sky is（）.

A. Sirius
B. Canopus
C. Venus
D. Jupiter

查看答案

单选题

Perihelion is the point where the Sun（）.

A. is nearest to the Earth
B. is farthest from the Earth
C. is on the opposite side of the Earth from the Moon
D. and Moon and Earth are in line

查看答案

单选题

The angle measured at the observer’s meridian from the elevated pole，clockwise or counterclockwise up to 180°，to the vertical circle of the body is the（）.

A. local hour angle
B. azimuth angle
C. meridian angle
D. longitude

查看答案

单选题

As observed from the Earth，the angle between lines from the Earth to the Sun and the Earth to an inferior planet is known as（）.

A. elongation
B. conjunction
C. opposition
D. quadrature

查看答案