A motorboat pulling a water skier in Victoria, Australia. For such activities, boats often have a high power-to-weight ratio and a hull design which allows for easy planing.

Photograph: Fir0002

A soybean cyst nematode (Heterodera glycines), together with an egg, as viewed through a low-temperature scanning electron microscope at 1000x magnification. This nematode infects the roots of soybeans, and the female nematode eventually becomes a cyst. Infection causes various symptoms that may include chlorosis of the leaves and stems, root necrosis, loss in seed yield and suppression of root and shoot growth.

Photograph: Agricultural Research Service

Dead Confederate troops behind the stone wall of Marye's Heights, killed during the Second Battle of Fredericksburg, Virginia, part of the eastern portion of the May 1863 Chancellorsville Campaign. At the wall, Confederate forces pushed back two waves of Union Army assaults before being overrun and forced to withdraw. Though the Union forces under Maj. Gen. John Sedgwick attempted to march on Chancellorsville, they were delayed by Confederate attacks and, the following morning, driven back.

Fought from April 30 to May 6, 1863, the Chancellorsville campaign saw Gen. Robert E. Lee's Confederate Army of Northern Virginia repel a force twice its size, Union Army Maj. Gen. Joseph Hooker's Army of the Potomac. However, in doing so they took numerous casualties and lost Lt. Gen. Thomas J. "Stonewall" Jackson to friendly fire.

Photograph: Andrew J. Russell; restoration: Lise Broer

The earliest reliably dated photograph of people, taken by Louis Daguerre one spring morning in 1838 from the window of the Diorama, where he lived and worked. It bears the caption huit heures du matin (8 a.m.). Though it shows the busy Boulevard du Temple, the long exposure time (about ten or twelve minutes) meant that moving traffic cannot be seen; however, the bootblack and his customer at lower left remained still long enough to be distinctly visible. The building signage at the upper left shows that the image is laterally (left-right) reversed, as were most daguerreotypes.

Photograph: Louis Daguerre

The heath fritillary (Melitaea athalia) is a species of butterfly in the family Nymphalidae, which can be found in heathland, grassland, and coppiced woodlands throughout the Palaearctic. They typically fly close to the ground, though they are generally sedentary and will rarely fly further than 100 metres (330 ft) at a time.

Photograph: Darius Baužys

Output from a shallow water equation model of water in a bathtub. The water experiences five splashes which generate surface gravity waves that propagate away from the splash locations and reflect off the bathtub walls.

The shallow water equations are a set of hyperbolic partial differential equations that describe the flow below a pressure surface in a fluid. They are derived from depth-integrating the Navier–Stokes equations in cases where the horizontal length scale is much greater than the vertical length scale. The shallow water equations can also be simplified to the commonly used 1-D Saint Venant equation.

Animation: Dan Copsey

A juvenile European shag (Phalacrocorax aristotelis), photographed in the south of Cres, Croatia. This species of cormorant, first described by Carl Linnaeus in 1761, lives along the rocky coasts of western and southern Europe, southwest Asia, and north Africa. These birds eat a wide variety of fish, diving to depths of 45 m (148 ft) to find their prey.

Photograph: Julius Rückert

Edward Gibbon (1737–1794) was an English historian who published The History of the Decline and Fall of the Roman Empire in six volumes between 1776 and 1788. Born in Putney, Surrey, he became a voracious reader while being raised by his aunt, and was sent to study at Magdalen College, Oxford, and in Switzerland. Returning to England, in 1761 Gibbon published his first book, Essai sur l'Étude de la Littérature. This was well received, but Gibbon's next book was a failure. In the early 1770s Gibbon began writing his history of the Roman Empire, which was received with great praise.

Painting: Henry Walton

Horseshoe Bend is a horseshoe-shaped meander of the Colorado River in the Glen Canyon National Recreation Area, located 5 miles (8 km) downstream from the Glen Canyon Dam and Lake Powell, near the town of Page, Arizona. It is accessible via hiking trail or an access road.

Photograph: Christian Mehlführer

Chandiroor Divakaran (b. 1946) is a Malayalam–language poet and folk song writer from Kerala, India. He has published numerous collections of poetry since his debut collection, Radha, in 1965.

Photograph: Augustus Binu

The Aitoff projection is a modified azimuthal map projection first proposed by David A. Aitoff in 1889. Based on the equatorial form of the azimuthal equidistant projection, Aitoff halved longitudes from the central meridian, projected by the azimuthal equidistant, and then stretched the result horizontally into a 2:1 ellipse.

Map: Strebe, using Geocart