Kilometre in the context of "Palmyra Atoll"

The square kilometre (square kilometer in American spelling; symbol: km) is a multiple of the square metre, the SI unit of area or surface area. In the SI unit of area (m), 1 km is equal to 1M(m).

This article contains a list of countries by length of coastline, in kilometers. Though the coastline paradox stipulates that coastlines do not have a well-defined length, there are various methods in use to measure coastlines through ratios and other metrics. A coastline of zero indicates that the country is landlocked.

The geography of Puerto Rico encompasses the geographical features of Puerto Rico, a Caribbean archipelagic and island nation centered around a collective identity based on its land, history, ethnicity, culture, and language, and organized as a self-governing unincorporated territory of the United States. Located between the Greater and Lesser Antilles in the northeastern Caribbean Sea, east of Hispaniola, west of Saint Thomas, north of Venezuela, and south of the Puerto Rico Trench, it consists of the eponymous main island of Puerto Rico and 142 smaller islands, islets, and cays, including San Juan Islet in the north, Vieques and Culebra islands in the Virgin Islands, and Palominos island and Icacos cay in La Cordillera nature reserve in the east, Caja de Muertos island in Caja de Muertos reserve, and Caracoles and Media Luna cays in La Parguera reserve in the south, and Mona, Monito, and Desecheo islands in the Mona Passage in the west.

Measuring 177 km (110 mi; 96 nmi) in length and 65 km (40 mi; 35 nmi) in width with a land area of 8,868 sq km (3,424 sq mi), the main island of Puerto Rico is the 4th largest in the Caribbean, 29th in the Americas, and 81st in the world, making it the 170th largest country or dependency by surface area. With 3.2 million residents, it is also the 4th largest in the Caribbean, 4th in the Americas, and 31st in the world, making it the 136th largest country or dependency by population.

Leros (Greek: Λέρος), also called Lero (from the Italian language), is a Greek island and municipality in the Dodecanese in the southern Aegean Sea. It lies 317 kilometres (197 miles; 171 nautical miles) from Athens's port of Piraeus, from which it can be reached by a nine-hour ferry ride or by a 45-minute flight from Athens. It is about 32 kilometres (20 miles) from Turkey. Leros is part of the Kalymnos regional unit. It has a population of 7,992 (2021).

Fiji, officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about 1,100 nautical miles (2,000 km; 1,300 mi) north-northeast of New Zealand. Fiji consists of an archipelago of more than 330 islands—of which about 110 are permanently inhabited—and more than 500 islets, amounting to a total land area of about 18,300 square kilometres (7,100 sq mi). The most outlying island group is Ono-i-Lau. About 87% of the total population live on the two major islands, Viti Levu and Vanua Levu. About three-quarters of Fijians live on Viti Levu's coasts, either in the capital city of Suva, or in smaller urban centres such as Nadi (where tourism is the major local industry) or Lautoka (where the sugar-cane industry is dominant). The interior of Viti Levu is sparsely inhabited because of its terrain.

The majority of Fiji's islands were formed by volcanic activity starting around 150 million years ago. Some geothermal activity still occurs today on the islands of Vanua Levu and Taveuni. The geothermal systems on Viti Levu are non-volcanic in origin and have low-temperature surface discharges (of between roughly 35 and 60 degrees Celsius (95 and 140 °F).

The kilometre per hour (SI symbol: km/h; non-SI abbreviations: kph, kmph, km/hr) is a unit of speed, expressing the number of kilometres travelled in one hour.

Sloane Square is a small hard-landscaped square on the boundaries of the central London districts of Belgravia and Chelsea, located 1.8 miles (2.9 km) southwest of Charing Cross, in the Royal Borough of Kensington and Chelsea. The area forms a boundary between the two largest aristocratic estates in London, the Grosvenor Estate and the Cadogan. The square was formerly known as 'Hans Town', laid out in 1771 to a plan of by Henry Holland Snr. and Henry Holland Jnr. Both the square and Hans Town were named after Sir Hans Sloane (1660–1753), an Anglo-Irish doctor who, jointly with his appointed trustees, owned the land at the time.

The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (AU), i.e. 30.9 trillion kilometres (19.2 trillion miles). The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 AU subtends an angle of one arcsecond (⁠1/3600⁠ of a degree). The nearest star, Proxima Centauri, is about 1.3 parsecs (4.2 light-years) from the Sun: from that distance, the gap between the Earth and the Sun spans slightly less than one arcsecond. Most stars visible to the naked eye are within a few hundred parsecs of the Sun, with the most distant at a few thousand parsecs, and the Andromeda Galaxy at over 700,000 parsecs.

The word parsec is a shortened form of a distance corresponding to a parallax of one second, coined by the British astronomer Herbert Hall Turner in 1913. The unit was introduced to simplify the calculation of astronomical distances from raw observational data. Partly for this reason, it is the unit preferred in astronomy and astrophysics, though in popular science texts and common usage the light-year remains prominent. Although parsecs are used for the shorter distances within the Milky Way, multiples of parsecs are required for the larger scales in the universe, including kiloparsecs (kpc) for the more distant objects within and around the Milky Way, megaparsecs (Mpc) for mid-distance galaxies, and gigaparsecs (Gpc) for many quasars and the most distant galaxies.

Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth of the average density of Earth, but is over 95 times more massive. Even though Saturn is almost as big as Jupiter, Saturn has less than a third of its mass. Saturn orbits the Sun at a distance of 9.59 AU (1,434 million km), with an orbital period of 29.45 years.

Saturn's interior is thought to be composed of a rocky core, surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium, and an outer layer of gas. Saturn has a pale yellow hue, due to ammonia crystals in its upper atmosphere. An electrical current in the metallic hydrogen layer is thought to give rise to Saturn's planetary magnetic field, which is weaker than Earth's, but has a magnetic moment 580 times that of Earth because of Saturn's greater size. Saturn's magnetic field strength is about a twentieth that of Jupiter. The outer atmosphere is generally bland and lacking in contrast, although long-lived features can appear. Wind speeds on Saturn can reach 1,800 kilometres per hour (1,100 miles per hour).

The coma is the nebulous envelope around the nucleus of a comet, formed when the comet passes near the Sun in its highly elliptical orbit. As the comet warms, parts of it sublimate; this gives a comet a diffuse appearance when viewed through telescopes and distinguishes it from stars. The word coma comes from the Greek κόμη (kómē), which means "hair" and is the origin of the word comet itself.

The coma is generally made of ice and comet dust. Water composes up to 90% of the volatiles that outflow from the nucleus when the comet is within 3–4 au (280–370 million mi; 450–600 million km) from the Sun. The H₂O parent molecule is destroyed primarily through photodissociation and to a much smaller extent photoionization. The solar wind plays a minor role in the destruction of water compared to photochemistry. Larger dust particles are left along the comet's orbital path while smaller particles are pushed away from the Sun into the comet's tail by light pressure.