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Preview Navigational Astronomy Questions

 

Polaris is part of what constellation? Cassiopeia  Center Orion Corona Borealis Ursa Minor
A first magnitude star is __________. 2.5 times as bright as a second magnitude star 3 times as bright as a second magnitude star 5 times as bright as a second magnitude star 10 times as bright as a second magnitude star
The expression "first magnitude" is usually used to refer only to bodies of magnitude __________. 1.5 and greater 0.5 and greater 1.25 and greater 1.0 and greater
Under ideal viewing conditions, the dimmest star that can be seen with the unaided eye is of what magnitude? First Third Fourth Sixth
Retrograde motion is the __________.

 movement of the points of intersection of the planes of the ecliptic and the equator

 apparent westerly motion of a planet with respect to stars

 movement of the celestial north pole in an elliptical pattern in space

 movement of a superior planet in its orbit about the Sun
The Star Lists in the Nautical Almanac are based on which of the following magnitudes? First Third Sixth Tenth
Your vessel is at the equator at midnight on 1 January, and a star is observed rising. At what time will this same star rise on 1 February, assuming your vessel's location is still at the equator? 2208 2110 2158 2317
A variable star is one that __________. has a changing declination is also known as a red giant exhibits a change in magnitude is increasing in SHA
A double star is a star that __________. suddenly becomes much brighter and then fades comprises two stars that appear close together is twice as bright as a single star has a declination equal to twice that of the Sun
A star that suddenly becomes several magnitudes brighter and then gradually fades is a __________. nebula double star nova variable star
A large group of stars revolving around a center is known as a __________. constellation cluster shower galaxy
A group of stars which appear close together and form a striking configuration such as a person or animal is a __________. shower cluster constellation galaxy
The Milky Way is an example of a __________. nebula galaxy nova cluster
The constellation that contains the pointer stars is __________. Ursa Major the Southern Cross Orion Pegasus
Miaplacidus is found in what constellation? Hydrus Puppis Carina Centaurus
The immediate surroundings of what constellation contain the most first magnitude stars? Orion Pegasus Cassiopeia Libra
Deneb is found in what constellation? Ursa Major Cygnus Pegasus Andromeda
Fomalhaut is found in what constellation? Pisces Leo Taurus Canis Major
Bellatrix is found in what constellation? Canis Minor Gemini Orion Taurus
Capella is found in what constellation? Crab Auriga Libra Gemini
Antares is found in what constellation? Libra Scorpio Corona Borealis Corvus
Denebola is found in what constellation? Hydrus Centaurus Leo Aquila
Altair is found in what constellation? Cygnus Aquila Capricorn Hercules
The magnitude of three stars is indicated. Which star is the brightest? Canopus - 0.9 Vega + 0.1 Cannot be determined; magnitude indicates size not brightness Antares + 1.2
The magnitude of three stars is indicated. Which star is the brightest? Antares + 1.2 Altair + 0.9 Vega + 0.1 Cannot be determined; magnitude indicates size not brightness
Inferior conjunction is possible for __________. Jupiter Saturn Venus Mars
Superior conjunction occurs when __________. two planets are in line the Sun is between the Earth and a planet a planet crosses the external plane of the ecliptic the Sun is at maximum declination north or south
Opposition occurs when __________. the Earth is between a planet and the Sun an inferior planet is at the maximum angle to the line of sight to the Sun the Sun, Earth, and Moon are at right angles the Sun's declination is 0° and is moving south
Planetary aberration is due, in part, to __________. rotation of the Earth on it's axis the body's orbital motion during the time required for its light to reach Earth a false horizon refraction of light as it enters the Earth's atmosphere
The spinning motion of a planet around its axis is called __________. orbit rotation space motion revolution
Mars is only seen at two phases, one of which __________. is conjunction occurs only at sunset or sunrise is the full phase occurs at or near 0° elongation
Mars will not be visible __________. from quadrature to opposition at opposition at elongation angles near 180° at conjunction
Diurnal aberration is due to __________. rotation of the Earth on its axis a false horizon the body's orbital motion during the time required for its light to reach the Earth motion of the Earth in its orbit
The planet Venus can be observed in the morning before sunrise if it is well to the __________. east of and higher than the Sun west of and higher than the Sun west of and lower than the Sun east of and lower than the Sun
Which is an inferior planet? Venus Mars Pluto Neptune
What is the brightest navigational planet? Saturn Mars Venus Jupiter
Other than the Sun and Moon, the brightest object in the sky is __________. Sirius Jupiter Venus Canopus
What celestial body may sometimes be observed in daylight? Sirius Saturn New Moon Venus
The largest of the navigational planets is __________. Mars Saturn Venus Jupiter
The Earth has the shape of a(n) __________. oblate spheroid oblate eggoid spheroid of revolution sphere
The parallel of latitude at 23°27'N is the __________. Arctic Circle ecliptic Tropic of Capricorn Tropic of Cancer
The parallel of latitude at 66°33'N is the __________. Tropic of Capricorn Tropic of Cancer ecliptic Arctic Circle
The parallel of latitude at 23°27'S is the __________. Tropic of Capricorn ecliptic Tropic of Cancer Arctic Circle
The precession of the equinoxes occurs in a(n) __________. easterly direction westerly direction southerly direction northerly direction
The precession of the equinoxes of the Earth is __________. caused by the elliptical shape of the Earth's orbit the irregularity of the Earth's orbit caused by influences of the Sun and Moon similar to a top spinning with its axis tilted the gradual increase in the period of rotation caused by the effects of the Moon
The spinning of a celestial body about its axis is known as __________. revolution space motion nutation rotation
"Rotation" is the __________. wobbling of the Earth about its axis motion of a celestial body in its orbit motion of bodies in the solar system relative to the stars spinning of a celestial body about its axis
A celestial body's complete orbit around another body is __________. space motion a rotation nutation a revolution
"Revolution" is the __________. wobbling of the Earth about its axis spinning of a celestial body about its axis motion of bodies in the solar system relative to the stars motion of a celestial body in its orbit
"Space motion" is the __________. irregularity in the motion of the Earth caused by other celestial bodies action causing precession of the equinoxes motion of a celestial body in its orbit motion of a body in the solar system relative to the stars
The motion of celestial bodies relative to other celestial bodies is known as __________. actual motion space motion apparent motion diurnal motion
The Sun at a maximum declination north would be approximately at __________. aphelion perihelion first point of Aries autumnal equinox
The Sun is closest to the Earth in what month? April January October July
Perihelion is the point where the Sun __________. is nearest to the Earth is farthest from the Earth is on the opposite side of the Earth from the Moon and Moon and Earth are in line
Aphelion is the point where the Sun __________. crosses the celestial equator is farthest from the Earth and Moon and Earth form a right angle and Moon and Earth are in line
During the month of October the Sun's declination is __________. north and decreasing south and increasing north and increasing south and decreasing
The point where the Sun is at maximum declination north or south is __________. a solstice perihelion an equinox aphelion
The points where the Sun is at 0° declination are known as __________. solstices perigee equinoxes apogee
The path that the Sun appears to take among the stars is the __________. Tropic of Cancer in the Northern Hemisphere zodiac line of apsides ecliptic
The first point of Aries is the point where the Sun is at __________. 0° declination going to northerly declinations 0° declination going to southerly declinations maximum declination north maximum declination south
The autumnal equinox is the point where the Sun is at __________. 0° declination going to southerly declinations maximum declination south maximum declination north 0° declination going to northerly declinations
The summer solstice is the point where the Sun is at __________. maximum declination north maximum declination south 0° declination going to northerly declinations 0° declination going to southerly declinations
The winter solstice is the point where the Sun is at __________. maximum declination north maximum declination south 0° declination going to southerly declinations 0° declination going to northerly declinations
The First Point of Aries is the position of the Sun on the celestial sphere on or about __________. September 21 December 21 June 21 March 21
The Moon and Sun are in line over your meridian. Tomorrow when the Sun is over your meridian, the Moon will be __________. over the meridian too about 6°West of the meridian about 11° west of the meridian about 12°East of the meridian
The Moon is subject to four types of libration. Which of the following is NOT one of these types of libration? Libration in latitude Physical libration Horizontal libration Diurnal libration
The Moon is subject to four types of libration. Which of the following is NOT one of these types of libration? Libration in longitude Libration in latitude Diurnal libration Vertical libration
The period of revolution of the Moon is __________. 365 days about 27.3 days 24 hours about 19 years
The period of rotation of the Moon on its axis is __________. 24 hours about 27.3 days 365 days about 19 years
The Moon is nearest to the Earth at __________. perigee the vernal equinox the full Moon the new Moon
The Moon is farthest from the Earth at __________. quadrature the lunar solstice apogee the full Moon
What condition exists at apogee? The Moon is farthest from the Sun. The Earth is farthest from the Moon. The Earth is closest to the Sun. The Moon is between the Earth and the Sun.
What condition exists at perigee? The Earth, Sun, and Moon are in line. The Earth, Sun, and Moon are at right angles. The Earth is farthest from the Sun. The Moon is closest to the Earth.
The major problem with Moon sights is the __________. approximations used in the solution caused by the variable horizontal parallax rapid changes in GHA and declination introduce errors into the calculations augmentation effect caused by the relatively short distance to the Moon lack of a well defined limb during certain phases and positions in the sky
Upper limb observations of the Moon are used more frequently than those of the Sun because of the location of the Moon in the sky and the __________. lesser distance between the Earth and the Moon effects of augmentation and horizontal parallax phase of the Moon rapid change in declination of the Moon
What happens because of augmentation? The horizon appears elevated when observing a bright Sun or Moon at low altitudes. The Moon appears larger as the elevation increases. The Sun appears larger when viewed against the darker background of the horizon. The Moon appears larger at the full Moon.
In low latitudes, a first quarter Moon will always rise at about __________. sunset 1200 LMT sunrise 2400 LMT
In low latitudes, the full Moon will always rise at about __________. sunset sunrise 1200 LMT 2400 LMT
In low latitudes, the new Moon will always rise at about __________. sunset 2400 LMT 1200 LMT sunrise
In low latitudes, a last quarter moon will always rise at about __________. 1200 LMT sunrise 2400 LMT sunset
The new Moon cannot be seen because the Moon is __________. between the Earth and the Sun below the horizon at quadrature in the opposite direction of the Sun
A plane that cuts the Earth's surface at any angle and passes through the center will always form __________. a great circle the equator a small circle a meridian
A plane that cuts the Earth's surface and passes through the poles will always form __________. a small circle a meridian the equator a loxodromic curve
The Sun's center may be coincident with both the celestial equator and the observer's prime vertical circle when __________. it crosses the June solstitial point it is in upper transit it crosses the December solstitial point its declination is zero
In which of the following does the arc of a great circle pass through a body and the celestial poles? diurnal circle altitude circle observer's meridian hour circle
The great circle of the celestial sphere that passes through the zenith, nadir, and the eastern point of the horizon is the __________. hour circle prime vertical principal vertical celestial meridian
Concerning a celestial observation, the azimuth angle is measured from the principal vertical circle to the __________. local celestial meridian vertical circle of the body Greenwich celestial meridian hour circle of the body
A celestial body will cross the prime vertical circle when the latitude is numerically __________. less than the declination and both are of contrary name greater than the declination and both are of contrary name greater than the declination and both are of the same name less than the declination and both are of the same name
The Sun's center is coincident with the principal vertical circle when __________. the hour circle and prime vertical are coincident the declination is zero degrees and the azimuth is exactly N 135°E in lower transit the declination is zero degrees and the azimuth is exactly N 135°W
The prime vertical is the great circle on the celestial sphere that passes through the __________. zenith, nadir and the east point of the horizon zenith, nadir and celestial body celestial poles and the celestial body celestial poles and the zenith
The great circle on the celestial sphere that passes through the zenith and the north and south poles is the __________. principal vertical ecliptic hour circle prime vertical
The prime vertical is the reference point from which the angle of which type of observation is measured? Sextant angle Azimuth Amplitude Local apparent noon
In the horizon system of coordinates what is the equivalent to the meridians on the Earth? Celestial meridians Hour circle Horizon Vertical circles
Sidereal hour angle is always __________. measured westward from the hour circle containing the first point of Aries subtracted from the LHA of the star to obtain the LHA of Aries measured from the point on the celestial sphere occupied by the Sun at the vernal equinox All of the above.
The angle that is measured westward from the first point of Aries to the hour circle of the body along the celestial equator is the __________. local sidereal time azimuth angle Greenwich sidereal angle sidereal hour angle
The principal vertical circle is that great circle on the celestial sphere that passes through the __________. zenith and the celestial body poles and Greenwich zenith and the north and south poles zenith and is parallel to the horizon
The arc of an hour circle between the celestial equator and a point on the celestial sphere, measured northward or southward through 90°, is the __________. latitude declination azimuth angle altitude
The daily path of a celestial body that is parallel to the celestial equator is the __________. hour circle diurnal circle altitude circle vertical circle
If an observer is at 35°N latitude, his zenith is __________. 35°N of the celestial equator 55°S of the celestial equator 55°N of the celestial equator at the north celestial pole
The small circle of the celestial sphere parallel to the celestial equator, and transcribed by the daily motion of the body, is called the __________. parallel of declination hour circle of the body parallel of altitude vertical circle of the body
In the celestial equator system of coordinates what is the equivalent to the meridians of the Earth system of coordinates? Hour circles Parallel of declination Vertical circles Horizon
The zenith is the point on the celestial sphere that is __________. 90° away from the poles over Greenwich on the eastern horizon directly over the observer
The point on the celestial sphere that is directly below an observer is the __________. node nadir zenith pole
The nadir is the point on the celestial sphere that is __________. directly below the observer over Greenwich on the western horizon 90° away from the zenith
The point on the celestial sphere that is directly below an observer is the __________. zenith nadir pole node
Zenith distance is equal to __________. Ho° + d 90° - z 90° - Ho 90° - d
90° - Ho = __________. zenith distance sextant altitude co-latitude LHA
The difference of latitude (l) between the geographic position (GP) of a celestial body and your position, at the time of upper transit, is represented by __________. codistance altitude zenith distance colatitude
At upper transit, if the zenith distance is 34°, the geographical distance from the observer to a body's GP is __________. 510 miles 1220 miles 2040 miles 2260 miles
In working out a local apparent noon sight for your latitude, you subtract the Ho from 90°. The 90° represents the angular distance from __________. your horizon to your zenith the geographical position of the Sun to the elevated pole the equator to the elevated pole your zenith to the elevated pole
If the Sun's observed altitude is 54°30', what is the zenith distance? 35°30' 14°30' 12°30' 45°30'
If the Sun's observed altitude is 27°12', the zenith distance is __________. 43°12' 62°48' 27°12' 152°48'
If the Sun's observed altitude is 47°50', the zenith distance is __________. 42°10' 42°50' 47°50' 132°10'
In the horizon system of coordinates what is equivalent to latitude on the Earth? Zenith distance Zenith Declination Altitude
In the horizon system of coordinates what is equivalent to longitude on the Earth? Azimuth angle Horizon Altitude Zenith distance
In the horizon system of coordinates what is equivalent to the equator on the Earth? Horizon Prime vertical circle Parallels of altitude Principal vertical circle
In the horizon system of coordinates what is equivalent to the poles on the Earth? Nodes Ecliptic poles Zenith, nadir Celestial poles
In the horizon system of coordinates what is the equivalent to the celestial equator of the celestial equator system? Principal vertical circle Prime vertical circle Prime meridian Horizon
In the horizon system of coordinates what is equivalent to the parallels of declination of the celestial equator system? Vertical circles Azimuth angle Zenith distance Parallels of altitude
In the horizon system of coordinates what is equivalent to the declination of the equator system? Zenith distance Altitude Azimuth angle Nadir
In the horizon system of coordinates what is equivalent to the Greenwich hour angle of the celestial equator system? Zenith distance Azimuth Coaltitude Altitude
In the horizon system of coordinates what is equivalent to the local hour angle of the celestial equator system? Zenith distance Altitude Azimuth Colongitude
In the horizon system of coordinates what is equivalent to the meridian angle of the celestial equator system? Altitude Colatitude Azimuth angle Zenith distance
If the right ascension of a body is 9 hours, it also __________. is 135° corresponds to an SHA for the body of 45° means that the GP of the body is in the western hemisphere All of the above.
The GHA of the first point of Aries is 315° and the GHA of a planet is 150°. What is the right ascension of the planet? 7 hours 11 hours 19 hours 23 hours
The angle measured eastward from the vernal equinox along the celestial equator often expressed in time units is the __________. local sidereal time sidereal hour angle Greenwich sidereal time right ascension
Right ascension is primarily used by the navigator for __________. calculating great circle sailings by the Ageton method calculating amplitudes plotting on star finders entering the Air Navigation Tables (Selected Stars) Pub 249
The celestial coordinate of a star that is relatively constant in value is the __________. meridian angle local hour angle sidereal hour angle Greenwich hour angle
The path of a celestial body during its daily apparent revolution around the Earth is called its __________. altitude circle circle of position ecliptic diurnal circle
The GHA of a star __________. increases at a rate of approximately 4° per hour decreases at a rate of approximately 15° per hour increases at a rate of approximately 15° per hour decreases at a rate of approximately 4° per hour
In the celestial equator system of coordinates, what is comparable to latitude on the terrestrial sphere? Declination Altitude Right ascension Celestial meridians
In the celestial equator system of coordinates what is equivalent to the longitude of the Earth system of coordinates? Greenwich hour angle Declination Zenith distance Azimuth angle
In the celestial equator system of coordinates what is equivalent to the colatitude of the Earth system of coordinates? Zenith distance Coaltitude Polar distance Declination
In the celestial equator system of coordinates what is NOT equivalent to the longitude of the Earth system of coordinates? Zn SHA LHA t
The difference (measured in degrees) between the GHA of the body and the longitude of the observer is the __________. meridian angle zenith distance SHA of the observer right ascension
The ecliptic is __________. the path the Sun appears to take among the stars a great circle on a gnomonic chart the path the Earth appears to take among the stars a diagram of the zodiac
The navigator is concerned with three systems of coordinates. Which system is not of major concern? Terrestrial Celestial equator Ecliptic Celestial horizon
The equator is __________. the line from which a celestial body's altitude is measured the primary great circle of the Earth perpendicular to the axis the line to which all celestial observations are reduced All of the above.
17 degrees of latitude is equal to __________. 68 miles 510 miles 1020 miles 4080 miles
15° of latitude is equal to __________. 600 miles 900 miles 1200 miles 1500 miles
A line on the Earth parallel to the equator is a __________. great circle meridian small circle gnomonic curve
A parallel of latitude other than the equator is a __________. loxodromic curve gnomonic curve great circle small circle
A plane perpendicular to the polar axis will never form what line on the Earth's surface?

 Meridian

 Equator

 Small circle

 Great circle
The angle at the pole measured through 180°From the prime meridian to the meridian of a point is known as __________. the departure Greenwich hour angle the polar arc longitude
The distance between any two meridians measured along a parallel of latitude and expressed in miles is the __________. difference in longitude departure mid-longitude
meridian angle
The distance between any two meridians measured along a parallel of latitude __________. increases in north latitude and decreases in south latitude decreases with increased latitude decreases as DLO increases increases with increased latitude
On 16 January, you take a sight of a star. The sextant altitude (hs) is 4°33.0'. The temperature is -10°C, and the barometer reads 992 millibars. The height of eye is 42 feet. The index error is 1.9' off the arc. What is the observed altitude (Ho)? 4°10.2' 4°14.3' 4°17.0' 4°24.1'
At about GMT 1436, on 3 December, the lower limb of the Moon is observed with a sextant having an index error of 2.5' on the arc. The height of eye is 32 feet. The sextant altitude (hs) is 3°38.8'. What is the observed altitude? Ho 4°18.6' Ho 4°29.1' Ho 4°36.3' Ho 4°42.2'
On 25 December you observe the Sun's lower limb. The sextant altitude (hs) is 4°06.9'. The height of eye is 47 feet and the index error is 1.6' on the arc. The temperature is 19°F and the barometer reads 1030.8 millibars. What is the observed altitude (Ho)? 3°57.4' 4°01.9' 4°02.5' 4°03.4'
In the Bay of Fundy, during twilight, you a take sight of Mars. The sextant altitude (hs) is 03°35.5'. Your height of eye is 32 feet and there is no index error. The air temperature is -10°C and the barometer reads 1010 millibars. What is the observed altitude (Ho)? 03°14.5' 03°15.8' 03°16.2' 03°28.8'
What is NOT a side of the navigational triangle used in sight reduction? Altitude Zenith distance Polar distance Colatitude
Which is NOT a side of the celestial navigational triangle? Co-declination Altitude Co-latitude Zenith distance
A vertex of the navigational triangle is NOT located at the __________. zenith elevated pole coaltitude celestial body
What great circle is always needed to form the astronomical triangle? Prime Vertical Circle Prime Meridian Celestial Equator Celestial Meridian
The navigational triangle uses parts of two systems of coordinates, one of which is the celestial equator system, the other system is the __________. ecliptic system horizon system terrestrial system astronomical system
The navigational triangle uses parts of two systems of coordinates, one of which is the horizon system and the other is the __________. ecliptic system terrestrial system celestial equator system astronautical system
In the navigational triangle, the angle at the elevated pole is the __________. azimuth angle meridian angle altitude right ascension
An azimuth angle for a body is measured from the __________. zenith distance observer's meridian body's meridian Greenwich meridian
The azimuth angle of a sun sight is always measured from the __________. first point of Aries principal vertical circle prime vertical circle Greenwich meridian
The angle measured from the observer's meridian, clockwise or counterclockwise up to 180°, to the vertical circle of the body is the __________. azimuth angle local hour angle observer's longitude meridian angle
The error in a sextant altitude caused by refraction is greatest when the celestial body is __________. rising near the horizon at or near transit high in the sky
Astronomical refraction causes a celestial body to appear __________. higher than its actual position to the right of its position in the Northern Hemisphere and to the left in the Southern Hemisphere lower than its actual position to the left of its position in the Northern Hemisphere and to the right in the Southern Hemisphere
A semidiameter correction is applied to observations of __________. the Moon Mars Jupiter All of the above.
The diameter of the Sun and Moon as seen from the Earth varies slightly but averages about __________. 1' 52' 15.5' 32'
Where do you find the semidiameter correction to be used to correct sextant observations of the stars? Table 25 in Bowditch contains the correction. A correction of -0.5' should be applied to all star sights. It is included in the altitude corrections inside the front cover of the Nautical Almanac. No semidiameter correction is used.
A phase correction is applied to observations of __________. planets stars the Sun All of the above.
Because the actual center of some planets may differ from the observed center, the navigator applies a correction known as the __________. phase correction refraction correction augmentation correction semidiameter correction
The phase correction should be applied to sights of Venus and Mars __________. during day time observations only during twilight observations only at all times when observed at altitudes of less than 25°
A phase correction may be applicable to correct the sextant altitude correction of __________. some planets any star the Sun third magnitude stars only
When applying a dip correction to the sighted sextant angle (hs), you always subtract the dip because you are correcting __________. hs to the visible horizon hs to the celestial horizon hs to the sensible horizon Ho to the celestial horizon
A correction for augmentation is included in the Nautical Almanac corrections for __________. the Moon Venus the Sun None of the above
Apparent altitude is sextant altitude corrected for __________. inaccuracies in the reading and reference level visibility and magnitude parallax and personal error All of the above.
What sextant correction corrects the apparent altitude to the equivalent reading at the center of the Earth? Semidiameter Parallax Augmentation Phase
A parallax correction is NOT applied to observations of the __________. stars Sun Planets Moon
When correcting the sextant altitude to apparent altitude you are correcting for inaccuracies in the reading and __________. the bending of the rays of light from the body for inaccuracies in the reference level the equivalent reading at the center of the body the equivalent reading from the center of the Earth
When correcting apparent altitude to observed altitude, you do NOT apply a correction for __________. inaccuracies in the reference level the bending of the rays of light from the body the equivalent reading to the center of the body the equivalent reading from the center of the Earth
When correcting the sextant altitude to apparent altitude you are correcting for inaccuracies in the reference level and __________. the equivalent reading from the center of the Earth for inaccuracies in the instrument the equivalent reading to the center of the body the bending of the rays of light from the body
The correction tables in the Nautical Almanac for use with Moon sights do NOT include the effects of __________. augmentation instrument error parallax semidiameter
The correction tables in the front of the Nautical Almanac for use with sun sights do NOT include the effects of __________. mean refraction parallax semidiameter irradiation
The radius of a circle of equal altitude for a body equals the body's __________. polar distance zenith distance declination altitude
The radius of a circle of equal altitude of a body is equal to the __________. polar distance coaltitude of the body altitude of the body codeclination of the body
A time diagram is a diagram on the plane of the __________. celestial horizon celestial meridian celestial equator principal vertical circle
A time diagram is a diagram of the celestial sphere as observed from above the __________. south celestial pole north celestial pole observer's meridian Greenwich meridian
The distance in miles between the circle of equal altitude for the observed altitude (Ho) and the circle of equal altitude for the computed altitude (Hc) is the __________. intercept zenith angle zenith distance equation of time
The equation of time is 12m 00s and the mean Sun is ahead of the apparent Sun. If you are on the central meridian of your time zone, at what zone time will the apparent Sun cross the meridian? 1212 1200 1148 It cannot be determined from the information given.
The equation of time is 8m 40s. The apparent Sun is ahead of the mean Sun. If you are on the central meridian of your time zone, the apparent Sun will cross your meridian at __________. 11-51-20 ZT 12-00-00 ZT 12-04-20 ZT 12-08-40 ZT
The equation of time is 8m 00s. The mean Sun is ahead of the apparent Sun. If you are 2°W of the central meridian of your time zone, when will the apparent Sun cross your meridian? 1208 1200 1216 1152
When the equation of time is taken from the Nautical Almanac for use in celestial navigation, it is used to determine __________. local mean time sunrise time of local apparent noon zone time
The primary use of apparent time in marine navigation is to __________. calculate sunrise or sunset determine the time of meridian transit enter an almanac determine zone time
The difference between local apparent time (LAT) and local mean time (LMT) is indicated by the __________. difference of longitude between the local and central meridian in time units longitude in time units zone description equation of time
The equation of time measures the __________. time between the passage of the mean sun and the apparent sun over a meridian difference between local apparent time and Greenwich apparent time longitude in time units difference between sidereal time and local time at the Greenwich meridian
Apparent time is based on __________. the Moon's motion in relation to the Sun a fictitious sun moving along the celestial equator the visible sun moving along the ecliptic the movement of the first point of Aries
When the time is based on the movement of the visible Sun along the ecliptic the time is known as __________. mean time apparent time visible time real time
The maximum difference between mean time and apparent time is __________. about 16 minutes equal to the longitude expressed in time units the difference between the GHA of mean sun and the first point of Aries 15° of arc
What is the equivalent of 83°29.6' in time units? 5h 18m 22.7s 5h 01m 42.3s 5h 47m 34.8s 5h 33m 58.4s
What is the equivalent of 0°48' in time units? 2 min. 12 sec. 2 min. 42 sec. 3 min. 02 sec. 3 min. 12 sec.
What is the equivalent of 37 min. 32 sec. in arc units? 6°38' 7°41' 9°23' 4°47'
What is the equivalent of 23 min. 20 sec. in arc units? 5°50' 12°32' 16°40' 9°28'
What is the equivalent of 10 min. 52 sec. in arc units? 0°47' 1°12' 2°43' 3°52'
What is the equivalent of 8 min. 56 sec. in arc units?
 2°14'
 0°28'
 1°12'
 0°46'
What is the equivalent of 4 min. 04 sec. in arc units? 1°01' 2°08' 8°08' 60°16'
What is the equivalent of 0 min. 16 sec. in arc units? 0°01' 0°32' 0°04' 0°16'
What is the equivalent of 1°53' in time units? 7 min. 32 sec. 3 min. 16 sec. 5 min. 28 sec. 6 min. 43 sec.
What is the equivalent of 2° 35' in time units? 10 min. 20 sec. 6 min. 43 sec. 9 min. 10 sec. 7 min. 06 sec.
What is the equivalent of 2°52' in time units? 9 min. 23 sec. 11 min. 28 sec. 11 min. 56 sec. 12 min. 18 sec.
What is the equivalent of 4°36' in time units? 9 min. 12 sec. 14 min. 36 sec. 15 min. 36 sec. 18 min. 24 sec.
What is the equivalent of 5°54' in time units? 20 min. 16 sec. 23 min. 36 sec. 25 min. 54 sec. 30 min. 27 sec.
What is the equivalent of 10°48' in time units? 50 min. 12 sec. 20 min. 12 sec. 43 min. 12 sec. 2 min. 39 sec.
What is the equivalent of 47 min. 20 sec. in arc units? 8°27' 11°50' 13°42' 13°56'
What is the equivalent of 42 min. 48 sec. in arc units? 18°16' 10°42' 11°19' 21°24'
The sidereal day begins when the __________. first point of Aries is over the lower branch of the reference meridian first point of Aries is over the upper branch of the reference meridian Sun is over the upper branch of the reference meridian Sun is over the lower branch of the reference meridian
When does the sidereal day begin? When the sun is over the upper branch of the reference meridian When the first point of Aries is over the upper branch of the reference meridian When the first point of Aries is over the lower branch of the reference meridian When the sun is over the lower branch of the reference meridian
With respect to the vernal equinox, what is the length of the year? anomalistic year tropical year sidereal year All of the above.
The approximate positions of the stars are based on sidereal time, which is based upon rotation of the Earth relative to __________. summer solstice winter solstice vernal equinox autumnal equinox
The sidereal day begins __________. at 0000 on 1 January (Sidereal Date) when the sun is over the first point of Aries when the first point of Aries is over 180° longitude when the first point of Aries is over the upper branch of the reference meridian
A sidereal day is shorter than a solar day. This difference is due to __________. the precession of the equinoxes irregularities in the daily rotational rate of the Sun the space motion of the solar system the use of different reference points
A sidereal day is approximately how much shorter than a solar day? 4 minutes 8 minutes 12 minutes 16 minutes
What is the length of the lunar day? 24h 50m 00s 23h 56m 04s 23h 03m 56s 24h 00m 00s
The lunar day is __________. longer than a solar day during the summer months and shorter in winter months shorter than a solar day the same length as the solar day longer than a solar day
Sidereal time is used by navigators when __________. determining local apparent time calculating the time of moonrise used in the form of LHA Aries used with the equation of time
Sidereal time is NOT used __________. in sight reductions of planet observations in sight reduction using Pub 249 as the basis for star charts to enter a star finder
Local sidereal time is equal to the __________. LHA of Aries GHA of Aries minus 180° right ascension of Aries plus 180° SHA of Aries
The lunar day is also known as the __________. lunitidal interval tidal day vulgar establishment of the port nodal day
The tropical year differs from which year by 20 minutes? Sidereal year Natural year Astronomical year Equinoctial year
The period of the Earth's revolution from perihelion to perihelion is the __________. anomalistic year sidereal year astronomical year solar year
At meridian transit, the diagram used by a navigator to illustrate the angles involved is based on the __________. celestial equator as observed from above the north celestial pole plane of the observer's meridian plane of the Greenwich meridian celestial equator as observed from above the south celestial pole
The GMT is 0445 and your zone description is +1. Your zone time is __________. 345 445 545 1545
A vessel is steaming in east longitude on January 25 and crosses the International Date Line on an eastbound course at 0900 zone time. What is the date and time at Greenwich when the vessel crosses the line? 0900, 24 January 2100, 24 January 2100, 25 January 0900, 26 January
The date is the same all over the world at __________. 0000 LMT for an observer at 90°E longitude 0000 GMT 1200 GMT no time
On 5 July at 1200 zone time, you cross the 180th meridian steaming westward. What is your local time? It is 1200, 4 July. It is 1200, 5 July. It is 1200, 6 July. It is 2400, 6 July.
Some locations maintain a zone time of -13. What are the Greenwich time and date if the zone time and date are 0152, 10 January? 1252, 9 January 1452, 9 January 0052, 11 January 1452, 11 January
Some locations maintain a zone time of -13. What are the zone time and date if the Greenwich time and date are 0152, 10 January? 0052, 9 January 0258, 9 January 1452, 10 January 0052, 11 January
The standard meridian for the time zone +1 is __________. 7 1/2°W 0° 7 1/2°E 15°W
You are on a vessel at 0400 ZT on 3 July, and the ZD for your position is -8. What is the GMT? 1200, 3 July 1200, 2 July 2000, 2 July 2000, 3 July
The standard time meridian for zone description -1 is __________. 0° 7 1/2°W 7 1/2°E 15°E
If the GMT is 1500, the time at 75°E longitude is __________. 1000 1500 1700 2000
The dividing meridian between zone descriptions -2 and -3 is __________. 15°30'E 30°00'E 37°30'E 45°00'E
On March 17, at 0500 zone time, you cross the 180th meridian steaming eastward to west longitude. What is your local time? You are in -12 time zone. It is 1700, March 18. It is 0500, March 16. It is 0500, March 18.
You are in LONG 165°E, zone time at 0400, 1 November. What is the zone time and date in LONG 165°W? 0600, 31 October 0600, 1 November 1800, 1 November 1800, 31 October
The dividing meridian between zone descriptions +7 and +8 is __________.

 105°00'W

 112°30'W

 117°00'W

 120°30'W
On November 1st the zone time is 1700 EST (ZD +5) in LONG 75°W. What is the corresponding zone time and date in LONG 135°E? 0700, November 1st 2200, October 31st 2200, November 1st 0700, November 2nd
The dividing meridian between zone descriptions +4 and +5 is __________. 67°30'W 67°30'E 90°00'W 75°00'E
You are in LONG 144°E. The date is 6 February, and the zone time is 0800. The Greenwich date and time are __________. 2200, 5 February 2300, 5 February 1700, 6 February 1800, 6 February
The navigator aboard a ship at approximately 165°E longitude observes the Sun at ZT 14-25-04 on 21 September. What is the GMT and Greenwich date of the observation? 02-25-04, 21 September 01-25-04, 21 September 03-25-04, 21 September 01-25-04, 20 September
A ship is in longitude 54°00'W on a true course of 270°. The ship's clocks are on the proper time zone. At what longitude should the clocks be changed to maintain the proper zone time? 45°00'W 52°30'W 60°00'W 67°30'W
A ship is in longitude 54°00'W on a true course of 090°. The ship's clocks are on the proper time zone. At what longitude should the clocks be changed to maintain the proper zone time? 67°30'W 60°00'W 52°30'W 45°00'W
Some places maintain a zone time of -13. What are the time and date at Greenwich if the zone time and date are 2152, 10 January? 1052, 9 January 0852, 10 January 1052, 10 January 1052, 11 January
Some locations maintain a zone time of -13. What are the zone time and date if the Greenwich time and date are 2152, 10 January? 1052, 9 January 0852, 10 January 1052, 10 January 1052, 11 January
The standard time meridian for description +12 is __________. 165.0°W 172.5°E 172.5°W 180.0°
The standard time meridian for zone description -12 is __________.
172.5°E 180.0° 172.5°W 165.0°E
The dividing meridian between zone descriptions -4 and -5 is __________. 60°00'E 67°30'E 60°00'W 75°00'E
The dividing meridian between zone descriptions -7 and -8 is __________.

 112°30'E

 118°30'E

 120°00'E

 116°30'W
The dividing meridian between zone descriptions -10 and -11 is __________. 135°30'E 145°00'E 150°00'E 157°30'E
On 6 July, at 1000 zone time, you cross the 180th meridian steaming westward. What is your local time? It is 1000, 7 July. It is 1000, 6 July. It is 2200, 7 July. It is 1000, 5 July.
Your longitude is 179°59'W. The LMT at this longitude is 23h 56m on the 4th day of the month. Six minutes later, your position is 179°59'E longitude. Your LMT and date are __________. 00h 02m on the 4th 00h 02m on the 6th 23h 50m on the 5th 00h 02m on the 5th
Your longitude is 179°59'W. The LMT at this longitude is 23h 56m of the 4th day of the month. Six minutes later your position is 179°59'E longitude. Your LMT and date is now __________. 00h 02m on the 5th 00h 02m on the 4th 00h 02m on the 6th 23h 50m on the 5th
The difference in local time between an observer on 114°W and one on 119°W is __________. 1.25 minutes 5 minutes 20 minutes 75 minutes
It is 1200 local time for an observer at 54°E longitude. Which statement is TRUE? It is afternoon at Greenwich. It is midnight at 126°E longitude. The observer is in time zone -4. All of the above.
The LMT of sunrise on the standard meridian is 0552. Your longitude is 99°15'E. What is your ZT of sunrise? 0512

 0529

 0552

 0615
Your longitude is 124°E, and your local mean time is 0520 on the 5th of the month. The mean time and date at Greenwich is __________. 1336 on the 5th 2104 on the 4th 2104 on the 5th 1336 on the 4th
The Local mean time of LAN is 1152. Your longitude is 73°15'E. What time would you use to enter the Nautical Almanac to determine the declination of the Sun at LAN? 0652 0659 1859 1852
The LMT of LAN is 1210. Your longitude is 70°30'E. Which time would you use to enter the Nautical Almanac to determine the declination of the Sun at LAN? 1842 1652 0728 0652
The change in the length of day becomes greater as latitude increases because of the __________. inclination of the diurnal circle to the equator increased obliquity of the celestial sphere decreasing distance between the terrestrial meridians changing distance between the earth and the sun
The change in the length of the day becomes greater as latitude increases because of the __________. path of the ecliptic relative to the equator changing distance between the Earth and the Sun decreasing distance between meridians increased obliquity of the Sun's diurnal circle
Which condition exists at the summer solstice in the Northern Hemisphere? The Northern Hemisphere is having short days and long nights. The north polar regions are in continual darkness. The Sun shines equally on both hemispheres. The Southern Hemisphere is having winter.
During one synodic rotation, a body makes one complete turn relative to the __________. Sun Earth vernal equinox stars
The measurement of local time is based on the passage of the Sun over the __________. lower branch of the observer's meridian lower branch of the Greenwich meridian upper branch of the observer's meridian upper branch of the Greenwich meridian
The reference point for determination of GMT is the passage of the mean sun over what line? 180° longitude Observer's meridian First point of Aries 0° longitude
The mean sun used to measure time moves __________. along the celestial equator at 15° per day along the ecliptic at 15° per hour along the ecliptic at 15° per day along the celestial equator at 15° per hour
A mean sun is used as the reference for solar time for three reasons. Which reason is NOT a cause for use of a mean sun? There are variations in the Earth's rotational speed. Measurement of time is along the celestial equator. The speed of the Earth's revolution is not constant. The motion of the apparent sun is along the ecliptic.
During daylight savings time the meridian used for determining the time is located farther __________. west in west longitude and east in east longitude west east east in west longitude and west in east longitude
During daylight savings time the meridian used for determining the time is located farther __________. east in west longitude and west in east longitude west west in west longitude and east in east longitude east
Daylight savings time is a form of zone time that adopts the time __________. two zones to the east one zone to the west two zones to the west one zone to the east
Daylight savings time is a form of zone time that adopts the time __________. one zone to the west two zones to the west two zones to the east one zone to the east
Universal time (UTI) is another name for __________. ephemeris time atomic time sidereal time Greenwich mean time