CompassA modern military compass, with included sight device for aligningA compass is a device that shows the cardinal directions used for navigation and geographic orientation. It typically consists of a magnetized needle or another element, such as a compass card or compass rose, that pivots to align itself with magnetic north. Other methods may be used, including gyroscopes, magnetometers, and GPS receivers.
Magnetic deviationMagnetic deviation is the compass error caused by local magnetic fields generated by nearby ferrous materials or electrical equipment, which distort the Earth's magnetic field in the vicinity of the compass. It is a local effect: the amount and direction of deviation depend on the specific location of the compass within a vessel, aircraft, or vehicle, and can vary even within the same craft. If not corrected, deviation can lead to inaccurate bearings.
Earth's magnetic fieldEarth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun.
Edmond HalleyEdmond (or Edmund) HalleyFRS (; 8 November[O.S. 29 October] 1656 – 25 January 1742[O.S. 14 January 1741]) was an English astronomer, mathematician and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720. From an observatory he constructed on Saint Helena in 1676–77, Halley catalogued the southern celestial hemisphere and recorded a transit of Mercury across the Sun.
Atlantic OceanThe Atlantic Ocean is the second largest of the world's five oceans, with an area of about 85,133,000 square kilometers (32,870,000 sq mi). It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for separating the New World of the Americas (North America and South America) from the Old World of Afro-Eurasia (Africa, Asia, and Europe).
North PoleThe North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface. It is called the True North Pole to distinguish from the Magnetic North Pole. The North Pole is by definition the northernmost point on the Earth, lying antipodally to the South Pole. It defines geodetic latitude 90° North, as well as the direction of true north.
True northTrue north is the direction along Earth's surface towards the place where the imaginary rotational axis of the Earth intersects the surface of the Earth on its northern half, the True North Pole. True south is the direction opposite to the true north. It is important to make the distinction from magnetic north, which points towards an ever changing location close to the True North Pole determined by Earth's magnetic field.
North magnetic poleThe north magnetic pole, also known as the magnetic north pole, is a point on the surface of Earth's Northern Hemisphere at which the planet's magnetic field points vertically downward (in other words, if a magnetic compass needle is allowed to rotate in three dimensions, it will point straight down). There is only one location where this occurs, near (but distinct from) the geographic north pole.
Magnetic dipMagnetic dip, dip angle, or magnetic inclination is the angle made with the horizontal by Earth's magnetic field lines. This angle varies at different points on Earth's surface. Positive values of inclination indicate that the magnetic field of Earth is pointing downward, into Earth, at the point of measurement, and negative values indicate that it is pointing upward.
Polar wanderPolar wander is the motion of a pole in relation to some reference frame. It can be used, for example, to measure the degree to which Earth's magnetic poles have been observed to move relative to the Earth's rotation axis.
Bowditch's American Practical NavigatorThe American Practical Navigator (colloquially often referred to as Bowditch), originally written by Nathaniel Bowditch, is an encyclopedia of navigation. It serves as a valuable handbook on oceanography and meteorology, and contains useful tables and a maritime glossary. In 1867 the copyright and plates were bought by the Hydrographic Office of the United States Navy.
Contour lineA contour line (also isoline, isopleth, isoquant or isarithm) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value to the state. It is a plane section of the three-dimensional graph of the function f ( x , y ) {\displaystyle f(x,y)} parallel to the ( x , y ) {\displaystyle (x,y)} -plane.*As an Amazon Associate I earn from qualifying purchases.