Navigation in the context of Celestial dome

The English-speaking world comprises the 88 countries and territories in which English is an official, administrative, or cultural language. In the early 2000s, between one and two billion people spoke English, making it the largest language by number of speakers, the third largest language by number of native speakers and the most widespread language geographically. The countries in which English is the native language of most people are sometimes termed the Anglosphere. Speakers of English are called Anglophones.

Early Medieval England was the birthplace of the English language; the modern form of the language has been spread around the world since the 17th century, first by the worldwide influence of England and later the United Kingdom, and then by that of the United States. Through all types of printed and electronic media of these countries, English has become the leading language of international discourse and the lingua franca in many regions and professional fields, such as science, navigation and law.

Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the surface of the Earth without relying solely on estimated positional calculations, commonly known as dead reckoning. Celestial navigation is performed without using satellite navigation or other similar modern electronic or digital positioning means.

Celestial navigation uses "sights," or timed angular measurements, taken typically between a celestial body (e.g., the Sun, the Moon, a planet, or a star) and the visible horizon. Celestial navigation can also take advantage of measurements between celestial bodies without reference to the Earth's horizon, such as when the Moon and other selected bodies are used in the practice called "lunars" or the lunar distance method, used for determining precise time when time is unknown.

Maritime history is the study of human interaction with and activity at sea. It covers a broad thematic element of history that often uses a global approach, although national and regional histories remain predominant. As an academic subject, it often crosses the boundaries of standard disciplines, focusing on understanding humankind's various relationships to the oceans, seas, and major waterways of the globe. Nautical history records and interprets past events involving ships, shipping, navigation, and seafarers.

Maritime history is the broad overarching subject that includes fishing, whaling, international maritime law, naval history, the history of ships, ship design, shipbuilding, the history of navigation, the history of the various maritime-related sciences (oceanography, cartography, hydrography, etc.), sea exploration, maritime economics and trade, shipping, yachting, seaside resorts, the history of lighthouses and aids to navigation, maritime themes in literature, maritime themes in art, the social history of sailors and passengers and sea-related communities. There are a number of approaches to the field, sometimes divided into two broad categories: Traditionalists, who seek to engage a small audience of other academics, and Utilitarians, who seek to influence policy makers and a wider audience.

A spacecraft is a vehicle that is designed to fly and operate in outer space. Spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. All spacecraft except single-stage-to-orbit vehicles cannot get into space on their own, and require a launch vehicle (carrier rocket).

On a sub-orbital spaceflight, a space vehicle enters space and then returns to the surface without having gained sufficient energy or velocity to make a full Earth orbit. For orbital spaceflights, spacecraft enter closed orbits around the Earth or around other celestial bodies. Spacecraft used for human spaceflight carry people on board as crew or passengers from start or on orbit (space stations) only, whereas those used for robotic space missions operate either autonomously or telerobotically. Robotic spacecraft used to support scientific research are space probes. Robotic spacecraft that remain in orbit around a planetary body are artificial satellites. To date, only a handful of interstellar probes, such as Pioneer 10 and 11, Voyager 1 and 2, and New Horizons, are on trajectories that leave the Solar System.

A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as the meridian arc length corresponding to one minute (⁠1/60⁠ of a degree) of latitude at the equator, so that Earth's polar circumference is very near to 21,600 nautical miles (that is 60 minutes × 360 degrees). Today the international nautical mile is defined as exactly 1,852 metres (about 6,076 ft; 1.151 mi). The derived unit of speed is the knot, one nautical mile per hour.

The nautical mile is not part of the International System of Units (SI), nor is it accepted for use with SI. However, it is still in common use globally in air, marine, and space contexts due to its correspondence with geographic coordinates.

In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, which may be centered on Earth or the observer. If centered on the observer, half of the sphere would resemble a hemispherical screen over the observing location.

The celestial sphere is a conceptual tool used in spherical astronomy to specify the position of an object in the sky without consideration of its linear distance from the observer. The celestial equator divides the celestial sphere into northern and southern hemispheres.

A 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.

Compasses often show angles in degrees: north corresponds to 0°, and the angles increase clockwise, so east is 90°, south is 180°, and west is 270°. These numbers allow the compass to show azimuths or bearings which are commonly stated in degrees. If local variation between magnetic north and true north is known, then direction of magnetic north also gives direction of true north.

Trigonometry (from Ancient Greek τρίγωνον (trígōnon) 'triangle' and μέτρον (métron) 'measure') is a branch of mathematics concerned with relationships between angles and side lengths of triangles. In particular, the trigonometric functions relate the angles of a right triangle with ratios of its side lengths. The field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies. The Greeks focused on the calculation of chords, while mathematicians in India created the earliest-known tables of values for trigonometric ratios (also called trigonometric functions) such as sine.

Throughout history, trigonometry has been applied in areas such as geodesy, surveying, celestial mechanics, and navigation.

The history of astronomy focuses on the efforts of civilizations to understand the universe beyond earth's atmosphere.Astronomy is one of the oldest natural sciences, achieving a high level of success in the second half of the first millennium. Astronomy has origins in the religious, mythological, cosmological, calendrical, and astrological beliefs and practices of prehistory. Early astronomical records date back to the Babylonians around 1000 BC. There is also astronomical evidence of interest from early Chinese, Central American and North European cultures.

Astronomy was used by early cultures for timekeeping, navigation, spiritual and religious practices, and agricultural planning. Ancient astronomers observed and charted the skies in an effort to learn about the workings of the universe. During the Renaissance Period, revolutionary ideas emerged about astronomy. One such idea was contributed in 1543 by Polish astronomer Nicolaus Copernicus, who developed a heliocentric model that depicted the planets orbiting the sun. This was the start of the Copernican Revolution, with the invention of the telescope in 1608 playing a key part. Later developments included the reflecting telescope, astronomical photography, astronomical spectroscopy, radio telescopes, cosmic ray astronomy, infrared telescopes, space telescopes,ultraviolet astronomy, X-ray astronomy, gamma-ray astronomy, space probes, neutrino astronomy, and gravitational-wave astronomy.

A landmark is a recognizable natural or artificial feature used for navigation, a feature that stands out from its near environment and is often visible from long distances.

In modern-day use, the term can also be applied to smaller structures or features that have become local or national symbols.

Lynches River, named for Thomas Lynch, Jr., signer of the Declaration of Independence, rises in North Carolina near Waxhaw, North Carolina, at about 700 feet (210 m) elevation, flowing only a short distance to the South Carolina border, and thence to join the Pee Dee River near Johnsonville. It is about 140 mi (230 km) long and the drainage area is 1,030 square miles (2,700 km).

Several sections of the river have been designated by the state of South Carolina as a wild and scenic river, with the upper portions from Bishopville to the eastern boundary of Lynches River County Park receiving designation in 1994, and the lower 57-mile section designated in 2008. The river is a favorite for canoeing, but Hurricane Hugo in 1989 felled many trees, blocking the flow at places, making navigation difficult at low water and dangerous at high water. River enthusiasts have been gradually cleaning up the storm debris. The river is also a popular fishing spot, with sunfish, redbreast, catfish and largemouth bass.

In geodesy, the figure of the Earth is the size and shape used to model planet Earth. The kind of figure depends on application, including the precision needed for the model. A spherical Earth is a well-known historical approximation that is satisfactory for geography, astronomy and many other purposes. Several models with greater accuracy (including ellipsoid) have been developed so that coordinate systems can serve the precise needs of navigation, surveying, cadastre, land use, and various other concerns.

Circumnavigation is the complete navigation around an entire island, continent, or astronomical body (e.g. a planet or moon). This article focuses on the circumnavigation of Earth.

The first circumnavigation of the Earth was the Magellan Expedition, which sailed from Sanlucar de Barrameda, Spain in 1519 and returned in 1522, after crossing the Atlantic, Pacific, and Indian oceans. Since the rise of commercial aviation in the mid 20th century, circumnavigating Earth is straightforward, usually taking days instead of years. Today, the challenge of circumnavigating Earth has shifted towards human and technological endurance, speed, and less conventional methods.

Seamanship is the art, competence, and knowledge of operating a ship, boat or other craft on water. The Oxford Dictionary states that seamanship is "The skill, techniques, or practice of handling a ship or boat at sea."

It involves topics and development of specialised skills, including navigation and international maritime law and regulatory knowledge; weather, meteorology and forecasting; watchkeeping; ship-handling and small boat handling; operation of deck equipment, anchors and cables; ropework and line handling; communications; sailing; engines; execution of evolutions such as towing; cargo handling equipment, dangerous cargoes and cargo storage; dealing with emergencies; survival at sea and search and rescue; and fire fighting.

Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datum – a standardised geodetic datum – that is used, for example, as a chart datum in cartography and marine navigation, or, in aviation, as the standard sea level at which atmospheric pressure is measured to calibrate altitude and, consequently, aircraft flight levels. A common and relatively straightforward mean sea-level standard is instead a long-term average of tide gauge readings at a particular reference location.

The term above sea level generally refers to the height above mean sea level (AMSL). The term APSL means above present sea level, comparing sea levels in the past with the level today.

Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels.

"Sonar" can refer to one of two types of technology: passive sonar means listening for the sound made by vessels; active sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used for robot navigation, and sodar (an upward-looking in-air sonar) is used for atmospheric investigations. The term sonar is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic) to extremely high (ultrasonic). The study of underwater sound is known as underwater acoustics or hydroacoustics.

A navigator is the person on board a ship or aircraft responsible for its navigation. The navigator's primary responsibility is to be aware of ship or aircraft position at all times. Responsibilities include planning the journey, advising the ship's captain or aircraft commander of estimated timing to destinations while en route, and ensuring hazards are avoided. The navigator is in charge of maintaining the aircraft or ship's nautical charts, nautical publications, and navigational equipment, and they generally have responsibility for meteorological equipment and communications.With the advent of satellite navigation, the effort required to accurately determine one's position has decreased by orders of magnitude, so the entire field has experienced a revolutionary transition since the 1990s with traditional navigation tasks, like performing celestial navigation, being used less frequently. Using multiple independent position fix methods without solely relying on electronic systems subject to failure helps the navigator detect errors. Professional mariners are still proficient in traditional piloting and celestial navigation.

In navigation, dead reckoning is the process of calculating the current position of a moving object by using a previously determined position, or fix, and incorporating estimates of speed, heading (or direction or course), and elapsed time. The corresponding term in biology, to describe the processes by which animals update their estimates of position or heading, is path integration.

Advances in navigational aids that give accurate information on position, in particular satellite navigation using the Global Positioning System, have made simple dead reckoning by humans obsolete for most purposes. However, inertial navigation systems, which provide very accurate directional information, use dead reckoning and are very widely applied.

Satellite navigation (satnav) or satellite positioning is the use of artificial satellites for navigation or geopositioning. A global navigation satellite system (GNSS) provides coverage for any user on Earth, including air, land, and sea. There are four operational GNSS systems: the United States Global Positioning System (GPS), Russia's Global Navigation Satellite System (GLONASS), China's BeiDou Navigation Satellite System (BDS) and the European Union's Galileo. Furthermore, there are two regional navigation satellite systems (RNSS) in the form of Japan's Quasi-Zenith Satellite System (QZSS), and the Indian Regional Navigation Satellite System (IRNSS, also known as NavIC).

A satellite-based augmentation system (SBAS) is a system that is designed to enhance the accuracy of the global GNSS systems. The SBAS systems include Japan's Quasi-Zenith Satellite System (QZSS), India's GAGAN, and the European EGNOS, all of them based on GPS.