Approximately true-color image of Io from the Galileo spacecraft. The dark spot just left of the center is the erupting volcano Prometheus. The whitish plains on either side of it are coated with volcanically deposited sulfur dioxide frost, whereas the yellower regions contain a higher proportion of sulfur.

Io (/ˈaɪ.oʊ/), or Jupiter I, is the innermost and third-largest of the four Galilean moons of the planet Jupiter. Slightly larger than Earth’s moon, Io is the fourth-largest moon in the Solar System, has the highest density of any moon, the strongest surface gravity of any moon, and the lowest amount of water (by atomic ratio) of any known astronomical object in the Solar System. It was discovered in 1610 by Galileo Galilei and was named after the mythological character Io, a priestess of Hera who became one of Zeus's lovers.

With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction generated within Io's interior as it is pulled between Jupiter and the other Galilean moons—Europa, Ganymede and Callisto. Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface. Io's surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of Io's silicate crust. Some of these peaks are taller than Mount Everest, the highest point on Earth's surface. Unlike most moons in the outer Solar System, which are mostly composed of water ice, Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Most of Io's surface is composed of extensive plains with a frosty coating of sulfur and sulfur dioxide. (Full article...)

Bust of Shen at the Beijing Ancient Observatory

Shen Kuo (Chinese: 沈括; 1031–1095) or Shen Gua, courtesy name Cunzhong (存中) and pseudonym Mengqi (now usually given as Mengxi) Weng (夢溪翁), was a Chinese polymathic scientist and statesman of the Song dynasty (960–1279). Shen was a master in many fields of study including mathematics, optics, and horology. In his career as a civil servant, he became a finance minister, governmental state inspector, head official for the Bureau of Astronomy in the Song court, Assistant Minister of Imperial Hospitality, and also served as an academic chancellor. At court his political allegiance was to the Reformist faction known as the New Policies Group, headed by Chancellor Wang Anshi (1021–1085).

In his Dream Pool Essays or Dream Torrent Essays (夢溪筆談; Mengxi Bitan) of 1088, Shen was the first to describe the magnetic needle compass, which would be used for navigation (first described in Europe by Alexander Neckam in 1187). Shen discovered the concept of true north in terms of magnetic declination towards the north pole, with experimentation of suspended magnetic needles and "the improved meridian determined by Shen's [astronomical] measurement of the distance between the pole star and true north". This was the decisive step in human history to make compasses more useful for navigation, and may have been a concept unknown in Europe for another four hundred years (evidence of German sundials made circa 1450 show markings similar to Chinese geomancers' compasses in regard to declination). (Full article...)

Traprock cliffs on Chauncey Peak, Connecticut

The Metacomet Ridge, Metacomet Ridge Mountains, or Metacomet Range of southern New England is a narrow and steep fault-block mountain ridge known for its extensive cliff faces, scenic vistas, microclimate ecosystems, and rare or endangered plants. The ridge is an important recreation resource located within 10 miles (16 km) of more than 1.5 million people, offering four long-distance hiking trails and over a dozen parks and recreation areas, including several historic sites. It has been the focus of ongoing conservation efforts because of its natural, historic, and recreational value, involving municipal, state, and national agencies and nearly two dozen non-profit organizations.

The Metacomet Ridge extends from Branford, Connecticut, on Long Island Sound, through the Connecticut River Valley region of Massachusetts, to northern Franklin County, Massachusetts, 2 miles (3 km) short of the Vermont and New Hampshire borders for a distance of 100 miles (160 km). It is geologically distinct from the nearby Appalachian Mountains and surrounding uplands, and is composed of volcanic basalt (also known as trap rock) and sedimentary rock in faulted and tilted layers many hundreds of feet thick. In most cases, the basalt layers are dominant, prevalent, and exposed. The ridge rises dramatically from much lower valley elevations, although only 1,200 feet (370 m) above sea level at its highest, with an average summit elevation of 725 feet (221 m). (Full article...)

Manchester (/ˈmæntʃɪstər, -tʃɛs-/) is a city in Greater Manchester, England. It had a population of 552,000 in 2021. It is bordered by the Cheshire Plain to the south, the Pennines to the north and east, and the neighbouring city of Salford to the west. The two cities and the surrounding towns form one of the United Kingdom's most populous conurbations, the Greater Manchester Built-up Area, which has a population of 2.87 million.

The history of Manchester began with the civilian settlement associated with the Roman fort (castra) of Mamucium or Mancunium, established in about AD 79 on a sandstone bluff near the confluence of the rivers Medlock and Irwell. Historically part of Lancashire, areas of Cheshire south of the River Mersey were incorporated into Manchester in the 20th century, including Wythenshawe in 1931. Throughout the Middle Ages Manchester remained a manorial township, but began to expand "at an astonishing rate" around the turn of the 19th century. Manchester's unplanned urbanisation was brought on by a boom in textile manufacture during the Industrial Revolution, and resulted in it becoming the world's first industrialised city. Manchester achieved city status in 1853. The Manchester Ship Canal opened in 1894, creating the Port of Manchester and linking the city to the Irish Sea, 36 miles (58 km) to the west. Its fortune declined after the Second World War, owing to deindustrialisation, and the IRA bombing in 1996 led to extensive investment and regeneration. Following considerable redevelopment, Manchester was the host city for the 2002 Commonwealth Games. (Full article...)

Hillsboro (/ˈhɪlzbəroʊ/ HILZ-burr-oh) is the fifth-largest city in the U.S. state of Oregon and is the county seat of Washington County. Situated in the Tualatin Valley on the west side of the Portland metropolitan area, the city hosts many high-technology companies, such as Intel, locally known as the Silicon Forest. At the 2020 census, the city's population was 106,447.

For thousands of years the Atfalati tribe of the Kalapuya lived in the Tualatin Valley near the later site of Hillsboro. The climate, moderated by the Pacific Ocean, helped make the region suitable for fishing, hunting, food gathering, and agriculture. Settlers founded a community here in 1842, later named after David Hill, an Oregon politician. Transportation by riverboat on the Tualatin River was part of Hillsboro's settler economy. A railroad reached the area in the early 1870s and an interurban electric railway about four decades later. These railways, as well as highways, aided the slow growth of the city to about 2,000 people by 1910 and about 5,000 by 1950, before the arrival of high-tech companies in the 1980s. (Full article...)

St Giles Church, Wormshill

Wormshill (/wɜːrmzˈhɪl/ wurmz-HIL), historically Wormsell, is a small village and civil parish within the Borough of Maidstone, Kent, England. The parish is approximately 7 miles (11 km) south of the Swale and 8 miles (13 km) east of Maidstone. The village of Frinsted lies 0.6 miles (1 km) to the east and Bicknor 1+1⁄2 miles (2.4 km) to the north-west; while Hollingbourne is 3 miles (5 km) to the south-west. The village lies on an exposed high point of the North Downs, within the Kent Downs Area of Outstanding Natural Beauty.

Archaeological and toponymic evidence of Wormshill's existence predates its appearance in the Domesday survey of 1086. The village contains a number of heritage-listed buildings, which include a Norman church, a public house and one of the oldest surviving post office buildings in the United Kingdom. The fields and woodland surrounding Wormshill have changed little in the past 500 years, and the village itself remains rural with a low population density compared to the national average. The population of 200 is a mixture of agricultural workers employed by local farms and professional residents who commute to nearby towns. (Full article...)

Aliso Creek flows underneath the Aliso Creek Road bridge before it enters Aliso and Wood Canyons Wilderness Park.

Aliso Creek is a 19.8-mile (31.9 km)-long, mostly urban stream in south Orange County, California. Originating in the Cleveland National Forest in the Santa Ana Mountains, it flows generally southwest and empties into the Pacific Ocean at Laguna Beach. The creek's watershed drains 34.9 square miles (90 km²), and it is joined by seven main tributaries. As of 2018, the watershed had a population of 144,000 divided among seven incorporated cities.

Aliso Creek flows over highly erosive marine sedimentary rock of late Eocene to Pliocene age. What would become the Aliso Creek watershed originally lay at the bottom of the Pacific Ocean, before being uplifted as recently as 10 million years ago. About 1.2 million years ago, the San Joaquin Hills began to uplift in the path of Aliso Creek. Occasionally swollen by wetter climates during glacial periods, the creek carved the deep water gap known today as Aliso Canyon, the main feature of Aliso and Wood Canyons Wilderness Park. (Full article...)

Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never far from the Sun, either as morning star or evening star. Aside from the Sun and Moon, Venus is the brightest natural object in Earth's sky, capable of casting visible shadows on Earth in dark conditions and being visible to the naked eye in broad daylight.

Venus is the second largest terrestrial object of the Solar System. It has a surface gravity slightly lower than on Earth and has a weak induced magnetosphere. The atmosphere of Venus consists mainly of carbon dioxide, and, at the planet’s surface, is the densest and hottest of the atmospheres of the four terrestrial planets. With an atmospheric pressure at the planet's surface of about 92 times the sea level pressure of Earth and a mean temperature of 737 K (464 °C; 867 °F), the carbon dioxide gas at Venus's surface is in the supercritical phase of matter. Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid, making it the planet with the highest albedo in the Solar System. It may have had water oceans in the past, but after these evaporated the temperature rose under a runaway greenhouse effect. The possibility of life on Venus has long been a topic of speculation but research has not produced convincing evidence of life. (Full article...)

Typical moorland scenery on Exmoor

Exmoor is loosely defined as an area of hilly open moorland in west Somerset and north Devon in South West England. It is named after the River Exe, the source of which is situated in the centre of the area, two miles north-west of Simonsbath. Exmoor is more precisely defined as the area of the former ancient royal hunting forest, also called Exmoor, which was officially surveyed 1815–1818 as 18,810 acres (7,610 ha) in extent. The moor has given its name to a National Park, which includes the Brendon Hills, the East Lyn Valley, the Vale of Porlock and 55 km (34 mi) of the Bristol Channel coast. The total area of the Exmoor National Park is 692.8 km² (267.5 sq mi), of which 71% is in Somerset and 29% in Devon.

The upland area is underlain by sedimentary rocks dating from the Devonian and early Carboniferous periods with Triassic and Jurassic age rocks on lower slopes. Where these reach the coast, cliffs are formed which are cut with ravines and waterfalls. It was recognised as a heritage coast in 1991. The highest point on Exmoor is Dunkery Beacon; at 519 metres (1,703 ft) it is also the highest point in Somerset. The terrain supports lowland heath communities, ancient woodland and blanket mire which provide habitats for scarce flora and fauna. There have also been reports of the Beast of Exmoor, a cryptozoological cat roaming Exmoor. Several areas have been designated as Nature Conservation Review and Geological Conservation Review sites. (Full article...)

Navenby village from the Viking Way

Navenby /ˈneɪvənbi/ is a village and civil parish in the North Kesteven district of Lincolnshire, England. Lying 8 miles (13 km) south from Lincoln and 9 miles (14 km) north-northwest from Sleaford, Navenby had a population of 2,128 in the 2011 census and in March 2011, it was named as the 'Best Value Village' in England following a national survey.

A Bronze Age cemetery and the remains of an Iron Age settlement have been discovered in the village. Historians also believe Navenby was a significant staging point on the Roman Ermine Street, as the Romans are reported to have maintained a small base or garrison in the village. Navenby became a market town after receiving a charter from Edward the Confessor in the 11th century. The charter was later renewed by William Rufus, Edward III and Richard II. When the market fell into disuse in the early 19th century, Navenby returned to being a village. (Full article...)

Courtroom during the trial

On 15 March 1921, Armenian student Soghomon Tehlirian assassinated Talaat Pasha—former grand vizier of the Ottoman Empire and the main architect of the Armenian genocide—in Berlin. At his trial, Tehlirian argued, "I have killed a man, but I am not a murderer"; the jury acquitted him.

Tehlirian came from Erzindjan in the Ottoman Empire but moved to Serbia before the war. He served in the Armenian volunteer units of the Russian army and lost most of his family in the genocide. Deciding to take revenge, he assassinated Harutian Mgrditichian, who helped the Ottoman secret police, in Constantinople. Tehlirian joined Operation Nemesis, a clandestine program carried out by the Dashnaktsutyun (the Armenian Revolutionary Federation); he was chosen for the mission to assassinate Talaat due to his previous success. Talaat had already been convicted and sentenced to death by an Ottoman court-martial, but was living in Berlin with the permission of the Government of Germany. Many prominent Germans attended Talaat's funeral; the German Foreign Office sent a wreath saying, "To a great statesman and a faithful friend." (Full article...)

The Imperial Trans-Antarctic Expedition of 1914–1917 is considered to be the last major expedition of the Heroic Age of Antarctic Exploration. Conceived by Sir Ernest Shackleton, the expedition was an attempt to make the first land crossing of the Antarctic continent. After Roald Amundsen's South Pole expedition in 1911, this crossing remained, in Shackleton's words, the "one great main object of Antarctic journeyings". Shackleton's expedition failed to accomplish this objective, but became recognized instead as an epic feat of endurance.

Shackleton had served in the Antarctic on the Discovery expedition of 1901–1904, and had led the Nimrod expedition of 1907–1909. In this new venture he proposed to sail to the Weddell Sea and to land a shore party near Vahsel Bay, in preparation for a transcontinental march via the South Pole to the Ross Sea. A supporting group, the Ross Sea party, would meanwhile establish camp in McMurdo Sound, and from there lay a series of supply depots across the Ross Ice Shelf to the foot of the Beardmore Glacier. These depots would be essential for the transcontinental party's survival, as the group would not be able to carry enough provisions for the entire crossing. The expedition required two ships: Endurance under Shackleton for the Weddell Sea party, and Aurora, under Aeneas Mackintosh, for the Ross Sea party. (Full article...)

A prominent landmark, St Thomas and St John with St Philip Church

Radcliffe is a market town in the Metropolitan Borough of Bury, Greater Manchester, England. It lies in the Irwell Valley 7 miles (11 km) north-northwest of Manchester and 3 miles (5 km) south-west of Bury and is contiguous with Whitefield to the south. The disused Manchester Bolton & Bury Canal bisects the town.

Evidence of Mesolithic, Roman and Norman activity has been found in Radcliffe and its surroundings. A Roman road passes through the area, along the border between Radcliffe and Bury. Radcliffe appears in an entry of the Domesday Book as "Radeclive" and in the High Middle Ages formed a small parish and township centred on the Church of St Mary and the manorial Radcliffe Tower, both of which are Grade I listed buildings. (Full article...)

The surrender of the Empire of Japan in World War II was announced by Emperor Hirohito on 15 August and formally signed on 2 September 1945, bringing the war's hostilities to a close. By the end of July 1945, the Imperial Japanese Navy (IJN) had become incapable of conducting major operations and an Allied invasion of Japan was imminent. Together with the United Kingdom and China, the United States called for the unconditional surrender of the Japanese armed forces in the Potsdam Declaration on 26 July 1945—the alternative being "prompt and utter destruction". While publicly stating their intent to fight on to the bitter end, Japan's leaders (the Supreme Council for the Direction of the War, also known as the "Big Six") were privately making entreaties to the publicly neutral Soviet Union to mediate peace on terms more favorable to the Japanese. While maintaining a sufficient level of diplomatic engagement with the Japanese to give them the impression they might be willing to mediate, the Soviets were covertly preparing to attack Japanese forces in Manchuria and Korea (in addition to South Sakhalin and the Kuril Islands) in fulfillment of promises they had secretly made to the United States and the United Kingdom at the Tehran and Yalta Conferences.

On 6 August 1945, at 8:15 AM local time, the United States detonated an atomic bomb over the Japanese city of Hiroshima. Sixteen hours later, American President Harry S. Truman called again for Japan's surrender, warning them to "expect a rain of ruin from the air, the like of which has never been seen on this earth." Late in the evening of 8 August 1945, in accordance with the Yalta agreements, but in violation of the Soviet–Japanese Neutrality Pact, the Soviet Union declared war on Japan, and soon after midnight on 9 August 1945, the Soviet Union invaded the Imperial Japanese puppet state of Manchukuo. Hours later, the United States dropped a second atomic bomb, this time on the Japanese city of Nagasaki. Following these events, Emperor Hirohito intervened and ordered the Supreme Council for the Direction of the War to accept the terms the Allies had set down in the Potsdam Declaration for ending the war. After several more days of behind-the-scenes negotiations and a failed coup d'état, Emperor Hirohito gave a recorded radio address across the Empire on 15 August announcing the surrender of Japan to the Allies. (Full article...)

Ice drilling allows scientists studying glaciers and ice sheets to gain access to what is beneath the ice, to take measurements along the interior of the ice, and to retrieve samples. Instruments can be placed in the drilled holes to record temperature, pressure, speed, direction of movement, and for other scientific research, such as neutrino detection.

Many different methods have been used since 1840, when the first scientific ice drilling expedition attempted to drill through the Unteraargletscher in the Alps. Two early methods were percussion, in which the ice is fractured and pulverized, and rotary drilling, a method often used in mineral exploration for rock drilling. In the 1940s, thermal drills began to be used; these drills melt the ice by heating the drill. Drills that use jets of hot water or steam to bore through ice soon followed. A growing interest in ice cores, used for palaeoclimatological research, led to ice coring drills being developed in the 1950s and 1960s, and there are now many different coring drills in use. For obtaining ice cores from deep holes, most investigators use cable-suspended electromechanical drills, which use an armoured cable to carry electrical power to a mechanical drill at the bottom of the borehole. (Full article...)

Generation Z (or more commonly Gen Z for short), colloquially known as zoomers, is the demographic cohort succeeding Millennials and preceding Generation Alpha. Researchers and popular media use the mid-to-late 1990s as starting birth years and the early 2010s as ending birth years. Most members of Generation Z are children of Generation X. (Full article...)

Clockwise from top: City of London in the foreground with Canary Wharf in the far background; Trafalgar Square; London Eye; Tower Bridge; and a London Underground roundel in front of Elizabeth Tower

London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a 50-mile (80 km) estuary down to the North Sea, and has been a major settlement for two millennia. The City of London, its ancient core and financial centre, was founded by the Romans as Londinium and retains its medieval boundaries. The City of Westminster, to the west of the City of London, has for centuries hosted the national government and parliament. Since the 19th century, the name "London" has also referred to the metropolis around this core, historically split between the counties of Middlesex, Essex, Surrey, Kent, and Hertfordshire, which since 1965 has largely comprised Greater London, which is governed by 33 local authorities and the Greater London Authority. (Full article...)

The United States of America is a federal republic consisting of 50 states, a federal district (Washington, D.C., the capital city of the United States), five major territories, and various minor islands. Both the states and the United States as a whole are each sovereign jurisdictions. The Tenth Amendment to the United States Constitution allows states to exercise all powers of government not delegated to the federal government. Each state has its own constitution and government, and all states and their residents are represented in the federal Congress, a bicameral legislature consisting of the Senate and the House of Representatives. Each state is represented by two senators, while representatives are distributed among the states in proportion to the most recent constitutionally mandated decennial census. Additionally, each state is entitled to select a number of electors to vote in the Electoral College, the body that elects the president of the United States, equal to the total of representatives and senators in Congress from that state. The federal district does not have representatives in the Senate, but has a non-voting delegate in the House, and it is also entitled to electors in the Electoral College. Congress can admit more states, but it cannot create a new state from territory of an existing state or merge of two or more states into one without the consent of all states involved, and each new state is admitted on an equal footing with the existing states. (Full article...)

Millennials, also known as Generation Y or Gen Y, are the demographic cohort following Generation X and preceding Generation Z. Researchers and popular media use the early 1980s as starting birth years and the mid-1990s as ending birth years, with the generation typically being defined as people born from 1981 to 1996. Most millennials are the children of baby boomers and older Generation X; millennials are often the parents of Generation Alpha. (Full article...)

Google Maps is a web mapping platform and consumer application offered by Google. It offers satellite imagery, aerial photography, street maps, 360° interactive panoramic views of streets (Street View), real-time traffic conditions, and route planning for traveling by foot, car, bike, air (in beta) and public transportation. , Google Maps was being used by over 1 billion people every month around the world. (Full article...)

England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea area of the Atlantic Ocean to the southwest. It is separated from continental Europe by the North Sea to the east and the English Channel to the south. The country covers five-eighths of the island of Great Britain, which lies in the North Atlantic, and includes over 100 smaller islands, such as the Isles of Scilly and the Isle of Wight. (Full article...)

This is a list of countries and dependencies by population. It includes sovereign states, inhabited dependent territories and, in some cases, constituent countries of sovereign states, with inclusion within the list being primarily based on the ISO standard ISO 3166-1. For instance, the United Kingdom is considered a single entity, while the constituent countries of the Kingdom of the Netherlands are considered separately. In addition, this list includes certain states with limited recognition not found in ISO 3166-1. Also given in a percentage is each country's population compared with the world population, which the United Nations estimates at 7.954 billion . (Full article...)

Europe is a continent that is part of Eurasia and is located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. Comprising the westernmost peninsulas of Eurasia, it shares the continental landmass of Afro-Eurasia with both Africa and Asia. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east. Europe is commonly considered to be separated from Asia by the watershed of the Ural Mountains, the Ural River, the Caspian Sea, the Greater Caucasus, the Black Sea and the waterways of the Turkish Straits. (Full article...)

Generation X (often shortened to Gen X) is the Western demographic cohort following the baby boomers and preceding the millennials. Researchers and popular media use the mid-to-late 1960s as starting birth years and the late 1970s to early 1980s as ending birth years, with the generation being generally defined as people born from 1965 to 1980. By this definition and U.S. Census data, there are 65.2 million Gen Xers in the United States as of 2019. Most members of Generation X are the children of the Silent Generation and early boomers; Xers are also often the parents of millennials and Generation Z. (Full article...)

Washington, D.C., formally the District of Columbia, also known as Washington, the District, or D.C., is the capital city and federal district of the United States. The city is located on the east bank of the Potomac River, which forms its southwestern border with Virginia, and it borders Maryland to its north and east. The city was named for George Washington, a Founding Father, commanding general of the Continental Army in the Revolutionary War, and the first president of the United States, and the district is named after Columbia, the female personification of the nation. (Full article...)