Wikipedia:Picture of the day/April 2016

A circa 1783 self-portrait of the French painter Joseph Ducreux (1735–1802) in the middle of a large yawn. Ducreux attempted to break free from the constraints of traditional portraiture in his depictions of subjects; another self-portrait, painted some ten years later, depicts him pointing at the viewer and laughing.

Painting: Joseph Ducreux

The Australasian swamphen (Porphyrio melanotus) is a species of swamphen previously considered a subspecies of the purple swamphen. Members of this species live in groups of 3–12 individuals and are known to group together and shriek loudly to defend nests successfully during attacks; when unsuccessful at repelling predators, they may abandon their nest sites. The Australasian swamphen can be found in eastern Indonesia (the Moluccas, Aru and Kai Islands), as well as in Papua New Guinea, Australia, and New Zealand.

Photograph: Toby Hudson

The Eckert IV projection is an equal-area pseudocylindrical map projection. The length of polar lines are half that of the equator, and lines of longitude are semiellipses, or portions of ellipses. It was first described by Max Eckert in 1906.

Map: Strebe, using Geocart

The Pinwheel Galaxy is a face-on spiral galaxy located 21 million light-years away in the constellation Ursa Major. It was first discovered by Pierre Méchain on March 27, 1781, and communicated to Charles Messier, who verified its position for inclusion in the Messier Catalogue as one of its final entries. This image, released on February 28, 2006, is composed of 51 individual exposures, as well as some extra ground-based photos. At the time of its release, it was the largest and most detailed image of a galaxy by the Hubble Space Telescope.

Photograph: European Space Agency and NASA

A view of the Wadi Bani Khalid from above. This wadi, located some 203 kilometres (126 mi) from Muscat, Oman, is the best-known of the Sharqiyah region. Its stream maintains a constant flow of water throughout the year, and large pools of water and boulders are scattered along the course of the wadi.

Photograph: Richard Bartz

James Watson (b. 1928) is an American molecular biologist, geneticist and zoologist, best known for discovering the double helix structure of DNA in 1953 jointly with Francis Crick. Watson, Crick, and Maurice Wilkins were awarded the 1962 Nobel Prize in Physiology or Medicine "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material". Educated at the University of Chicago and Indiana University, Watson met Crick at the University of Cambridge's Cavendish Laboratory in England, where they were still working when they deduced the structure. Watson wrote of the discovery in his book, The Double Helix (1968), and promoted further study of molecular biology while serving as director of Cold Spring Harbor Laboratory (CSHL) on Long Island, New York.

Photograph: Cold Spring Harbor Laboratory; edit: Jan Arkesteijn

The Pena National Palace is a Romanticist palace in Sintra, Portugal, built by Ferdinand II of Portugal on the site of a ruined monastery. The palace stands on the top of a hill in the Sintra Mountains, and on a clear day it can be easily seen from Lisbon and much of its metropolitan area. It is a national monument, UNESCO World Heritage Site, and considered one of the Seven Wonders of Portugal. It is also used for state occasions by the President of the Portuguese Republic and other government officials.

Photograph: Uwe Aranas

The Aqueduct of Segovia is a Roman aqueduct located in Segovia, Spain that transports water from the Rio Frio. It is thought to have been constructed during the 1st century CE. One of the most significant and best-preserved ancient monuments left on the Iberian Peninsula, the aqueduct is considered a symbol of Segovia and is present on the city's coat of arms.

Photograph: Bernard Gagnon

Balzhinima Tsyrempilov is a World Cup-winning and former world number-one archer from Russia. He has competed in both the 2004 and 2008 Summer Olympics, though he has not medalled.

Photograph: Аркадий Зарубин

Helmut Flieg (1913–2001) was a German writer best-known by the pseudonym Stefan Heym. He lived in the United States (or served in its army abroad) between 1935 and 1952, before moving back to his native Germany. He published works in English and German at home and abroad, including Nazis in the U.S.A. (1938), Goldsborough (1953), and Five Days in June (1977).

Photograph: Marcel Antonisse / Anefo

Stanislaus of Szczepanów (1030–1079) was a Bishop of Kraków known chiefly for having been martyred by the King Bolesław II the Generous of Poland. One of the first native Polish bishops, Stanislaus came into conflict with King Bolesław several times. In one case, the bishop is said to have resurrected a dead man so that he could bear witness regarding a sale of land. Another conflict, whose cause is disputed, led to Stanislaus excommunicating the King. In response, Bolesław killed the bishop and then had his body cut into pieces.

Illustration: Stanisław Samostrzelnik

Shearing the Rams is an 1890 oil painting on canvas by Australian artist Tom Roberts. It depicts sheep shearers plying their trade in a timber shearing shed. One of Australia's best-known paintings, it and other Australian Impressionist works gave visual expression to an emerging sense of national identity. The painting is held at the National Gallery of Victoria, Melbourne.

Painting: Tom Roberts

The Siberian rubythroat (Luscinia calliope) is a small passerine bird generally considered to be an Old World flycatcher of the family Muscicapidae. This migratory insectivorous species breeds in mixed coniferous forest with undergrowth in Siberia, where it nests near the ground. It winters in Thailand, India and Indonesia. It is an extremely rare vagrant to Western Europe and the Aleutian Islands.

Photograph: JJ Harrison

The Peirce quincuncial projection is a conformal map projection developed by Charles Sanders Peirce in 1879, while he was working at the U.S. Coast and Geodetic Survey. In the normal aspect Peirce's projection presents the Northern Hemisphere in a square; the Southern Hemisphere is split into four 90°–45°–45° triangles surrounding it so that the whole map forms a larger square.

Map: Strebe, using Geocart

Girl at Sewing Machine is a 1921 painting by Edward Hopper that is currently housed in the Museo Thyssen-Bornemisza in Madrid, Spain. The first of Hopper's "window paintings", it portrays a young girl sitting at a sewing machine facing a window on a beautiful sunny day. The location appears to be New York as is evident from the yellow bricks in the window.

Painting: Edward Hopper

Sarah Vaughan (1924–1990) was an American jazz singer who rose to fame in the 1940s and remained active for nearly five decades. Described by Scott Yanow as having "one of the most wondrous voices of the 20th century", Vaughan has received extended recognition, including induction into the New Jersey Hall of Fame, two entries in the Grammy Hall of Fame, and several tribute albums.

Photograph: William P. Gottlieb; Restoration: Adam Cuerden

A female Balearic green toad (Bufo balearicus), a lowland species of toad native to Italy.

Photograph: Richard Bartz

An illustration from Urania's Mirror (1825) depicting the constellation Libra. This faint constellation, which has no first magnitude stars, is located between Virgo to the west and Scorpius to the east. Both Roman and Babylonian astronomy likened the constellation to a pair of scales, though the Ancient Greeks held it to be the scorpion's claws. Libra is one of the constellations of the zodiac; in Western astrology, Libra covers the period between September 22 and October 21.

Illustration: Sidney Hall; restoration: Adam Cuerden

The mandarin duck (Aix galericulata) is a perching duck species endemic to East Asia but since introduced to Europe and the United States. It is medium-sized, at 41–49 cm (16–19 in) long with a 65–75 cm (26–30 in) wingspan. The species mainly eats plants and seeds, especially beech mast. It will also add snails, insects and small fish to its diet.

This specimen was photographed in Richmond Park, London.

Photograph: David Iliff

On April 20, 2010, the Deepwater Horizon, a semi-submersible Mobile Offshore Drilling Unit owned and operated by Transocean and drilling for BP in the Macondo Prospect oil field southeast of the Louisiana coast, exploded. The explosion killed eleven workers, injured sixteen others, and caused the Deepwater Horizon to catch fire and sink. The same blowout also caused a massive offshore oil spill in the Gulf of Mexico. This spill has been considered the largest accidental marine oil spill to date, as well as the largest environmental disaster in U.S. history.

Photograph: United States Coast Guard; edit: Ottojula and Mark Miller

An illustration from 1896 edition of James Fenimore Cooper's The Last of the Mohicans. Set during the French and Indian War, the novel details the transport of two young women to Fort William Henry. Among the caravan guarding the women are the frontiersman Natty Bumppo, the Major Duncan Heyward, and the Indians Chingachgook and Uncas. In this scene, Bumppo (disguised as a bear) fights against the novel's villain, Magua, as two of his compatriots look on.

Illustration: Frank T. Merrill; restoration: Chris Woodrich

A banknote for two Massachusetts shillings, or 1/10 of a Massachusetts pound, dated 1 May 1741. Massachusetts was the first of the Thirteen Colonies to have its own currency, authorizing the issuance of paper money in 1690; South Carolina would follow with its own pound in 1703. The pound saw heavy inflation and, in 1749, Massachusetts withdrew its paper money from circulation and returned to specie.

Banknote: Province of Massachusetts Bay; image courtesy of the National Numismatic Collection at the Smithsonian Institution

Inveraray Castle is a country house near Inveraray in the county of Argyll, in western Scotland, on the shore of Loch Fyne, Scotland’s longest sea loch. Designed in part by William Adam and Roger Morris, work on the Gothic Revival castle began in the 1740s. The castle, the seat of the Duke of Argyll, chief of Clan Campbell, is open to the public.

Photograph: Son of Groucho

Siproeta stelenes is a neotropical brush-footed butterfly in the family Nymphalidae found throughout Central and northern South America. Adults feed on flower nectar, rotting fruit, dead animals, and bat dung. This species is sometimes known as the malachite, named after a mineral which is similar in color to the bright green on the butterfly's wings.

Photograph: Böhringer Friedrich

Survivors of the Battle of Greece from the Māori Battalion performing a haka in Helwan, Egypt, for King George II of Greece. This infantry battalion of the New Zealand Army was raised in 1940 as part of the Second New Zealand Expeditionary Force, following pressure by some Māori Members of Parliament and organisations throughout the country. The battalion fought during the Greek, North African and Italian campaigns and gained a formidable reputation. After the war, the battalion contributed a contingent of personnel to serve in Japan as part of the British Commonwealth Occupation Force, before being disbanded in January 1946.

Photograph: Anonymous; restoration: Adam Cuerden

A Polish Nobleman is an oil painting on panel completed by Rembrandt in 1637. It depicts a man in a costume of either Polish szlachta or Eastern-European boyar nobility. His identity is unclear, and has given rise to several different interpretations. The painting is now in the National Gallery of Art in Washington, D.C.; its past owners have included Catherine II the Great and Andrew Mellon.

Painting: Rembrandt

Americae Sive Quartae Orbis Partis Nova Et Exactissima Descriptio is an ornate geographical map of the Americas made in 1562 by Spanish cartographer Diego Gutiérrez and Flemish artist Hieronymus Cock. The map encompasses the eastern coast of North America, the whole of Central and South America, and parts of the western coasts of Europe and Africa. This is the earliest scale wall map of the New World and the first to use the name "California". Two extant copies are known.

Map: Diego Gutiérrez and Hieronymus Cock

On the tram network of Melbourne, Australia, the C-class trams are 36 three-section Citadis 202 trams built by Alstom, France. Delivered in 2001–02, they were the first low-floor trams in Melbourne. They replaced the Z-class trams after the tram network was privatised.

Photograph: David Iliff

Aularches miliaris is a colorful grasshopper belonging to the family Pyrgomorphidae found in South and Southeast Asia. The species is heavy and sluggish, able to make only short leaps, and very visible on vegetation. The grasshopper's bright warning colours keep away predators, and it ejects a toxic foam when disturbed.

Photograph: Chris Woodrich

Stockholm Central Station, located in the district of Norrmalm at Vasagatan/Central Plan, is the largest railway station in Sweden. Designed by Adolf W. Edelsvärd and opened on 18 July 1871, it has over 200,000 visitors daily. Engineers use the heat generated by these visitors to help heat a nearby office building.

Photograph: Arild Vågen