Celestial Navigation Quiz

The practice of determining one's position on Earth or in space by observing and measuring the angles of celestial bodies such as the Sun, Moon, planets, and stars relative to the horizon.

Answer explanation

Answer: Celestial Navigation

Why is celestial navigation crucial for navigators?

Answer explanation

Celestial navigation is crucial for navigators as it provides a reliable backup method when electronic systems fail, ensuring continued navigation capabilities.

List all celestial bodies used commonly used for navigation.

Answer explanation

Answer: Sun, Moon, Planets (Venus, Mars, Jupiter, Saturn), Stars (57 Selected Navigational Stars, Polaris (North Star)

________________ is the point in a celestial body's orbit where it is closest to the Sun, while ________________ is the point in a celestial body's orbit where it is farthest from the Sun.

Canopus has an apparent magnitude of about -0.74, and Betelgeuse has an apparent magnitude of about 0.42. Which star appears brighter in the night sky?

• Canopus

• Betelgeuse

Fill the “Celestial Equator Coordinate System” column with the analogous terms from the Earth Coordinate System.

Earth Coordinate System

equator

Poles

Latitude

Answer explanation

Earth Coordinate System

equator

Poles

Latitude

Celestial Equator Coordinate System

celestial equator

celestial poles

Declination

Fill the “Horizon Coordinate System” column with the analogous terms from the Earth Coordinate System.

Earth Coordinate System

equator

Poles

Latitude

Answer explanation

Earth Coordinate System

equator

Poles

Latitude

Horizon Coordinate System

horizon

zenith; nadir

Altitude

The observer’s longitude is 80° E. The GHA of Aries is 070° and the SHA of a star is 090°. Find the following information about the star: a. GHA Star b. LHA Star c. Meridian Angle (t) Star d. Right Ascension (RA) Star e. Draw the time diagram corresponding to your answer.

Answer explanation

ANSWER KEY:

a.       GHA Star– 160°

b.       LHA Star – 240°

c.       Meridian Angle (t) – 120° E

d.       Right Ascension (RA) – 270°

e.       Draw the time diagram corresponding to your answer.

What is the term used to describe the discrepancy between true/apparent solar time, which is measured by the position of the Sun in the sky, and mean solar time, which is a uniform time scale based on a theoretical Sun moving at a constant rate?

Answer explanation

Answer: The equation of time.

True or False: The equation of time is always positive, meaning that true/apparent solar time is always ahead of mean solar time.

• True

• False

Answer explanation

Answer: False. The equation of time can be both positive and negative throughout the year, depending on the time of year. It is positive when apparent solar time is ahead of mean solar time and negative when it is behind.