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Local Hour Angle (LHA) is the angle between the observer's meridian and the hour circle passing through a celestial body, measured westward from 0° to 360°.

Polaris, also known as the North Star, is approximately situated at the celestial pole and is almost stationary in the sky, aiding in finding true North.

The ecliptic is the apparent path of the Sun across the celestial sphere over the course of a year, used to understand the movement of sun and planets.

Sight reduction is the process of converting the observed altitude of a celestial body into a line of position, using tables or calculations, for navigational purposes.

A great circle is any circle that divides the globe into two equal hemispheres. It's the shortest path between two points on the Earth's surface.

Altitude, or angular height, is the angle from the observer's horizon up to a celestial body. It is a critical component in determining one's position via celestial objects.

The Nautical Almanac contains daily positions of the sun, moon, planets, and stars at various times, essential for celestial navigation.

The celestial sphere is an imaginary sphere of indefinite radius centered on the observer. All celestial bodies seem to be projected upon this sphere.

The meridian passage refers to the time at which a celestial body crosses the meridian of the observer and achieves its highest altitude.

Dead reckoning is a method of estimating one's current position by advancing a known position using course, speed, time, and distance traveled.

The equinoctial, or celestial equator, is the projection of the Earth's equator onto the celestial sphere, dividing it into Northern and Southern hemispheres.

Sidereal Hour Angle (SHA) is the angular distance westward along the celestial equator from the vernal equinox to the hour circle of the celestial body.

The azimuth is the angle measured in degrees between the North point of the horizon and the point directly below a celestial body. It is used in conjunction with altitude to pinpoint a location on Earth.

A chronometer is a highly accurate timekeeping device, crucial for determining longitude by comparing local time to Greenwich Mean Time (GMT).

The prime vertical is a circle on the celestial sphere that lies in the vertical plane perpendicular to the observer's celestial horizon.

Declination is the angular distance of a celestial body north or south of the celestial equator, similar to latitude on Earth.

A sextant is a navigational instrument used to measure the angle of altitude of celestial bodies. It is crucial for determining latitude and longitude at sea.