The great-winged petrel (Pterodroma macroptera) is a species of petrel endemic to southern Australia and New Zealand; this specimen was photographed east of Tasmania. Two subspecies of the great-winged petrel are recognized.Photograph: JJ Harrison
NGC 2467 is a star-forming region with a visual appearance often likened to a skull or a mandrill. Located in the southern constellation of Puppis, it contains the open clusters Haffner 18 (centre) and Haffner 19 (middle right: located inside the smaller pink "eye"), as well as vast areas of ionised gas. The bright star at the centre of the largest pink region is HD 64315, a massive young star that is helping to shape the whole nebular region's structure.Photograph: European Southern Observatory
Shown here is a $20 note, dated 10 August 1861, which features a feminine allegory representing either Liberty, or perhaps America, in the center. The figure has a sword in her right hand and holds a striped shield, featuring a Bald Eagle at the top, in her left. This bill is scanned from the National Numismatic Collection at the National Museum of American History.
A diagram of a typical turbojet engine. Air is compressed as it enters the engine, and is mixed with fuel that burns in the combustion section. Released through the exhaust, the resulting hot gases provide forward thrust and turn the turbines that drive the fan blades of the compressor.Diagram: Jeff Dahl
The slender mongoose (Galerella sanguinea) is a common species of mongoose found throughout much of sub-Saharan Africa. Dozens of subspecies are known, and the fur color varies between subspecies. The slender mongoose tends to live alone or in pairs, and, although it is an opportunistic omnivore, it feeds primarily on insects.
The harlequin beetle (Acrocinus longimanus) is a large tropical longhorn beetle native to the Americas. The species' common name is derived from the elaborate pattern of black, red and greenish yellow markings on the wing covers of both sexes.Photograph: Didier Descouens
A diagram of a typical thermal power station, a type of power plant in which the prime mover is steam driven. Water is heated, turns into steam and spins a steam turbine, which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated; this is known as a Rankine cycle. For a more detailed overview of the process, consult the diagram's description.Diagram: BillC; modifications: MaCRoEco
The European bee-eater (Merops apiaster) is a near passerine bird in the bee-eater family Meropidae which breeds in southern Europe and in parts of north Africa and western Asia and winters in tropical Africa, India and Sri Lanka. The species predominantly feeds on insects, especially bees, wasps and hornets, which are caught in the air by sorties from an open perch.Photo: Pierre Dalous
The mosque at the Taj Mahal complex in Agra, India. This red sandstone building, on the western side of the complex, faces the west side of the mausoleum. In the forefront is a howz, meant for ablution. On the eastern side of the complex is the jawab ("answer"), a mirror image of the mosque except for the missing mihrab and different floor pattern; this jawab was mainly intended for architectural balance. Both were constructed in 1643.Photo: Muhammad Mahdi Karim
Spialia mafa is a species of butterfly in the spread-winged skipper subfamily that is found in south-western Africa. These skippers bask with their wings held wide open, but close the wings when at rest. The subfamily consists of seven tribes, a number which has increased in the past several decades as more tribes were recognized.Photo: Muhammad Mahdi Karim
A two-point equidistant projection of Eurasia. All distances of other points from the two points marked in red (45°N 40°E and 30°N 110°E) are correct. This map is a derivative of NASA's Blue Marble summer month composite, with oceans lightened to enhance legibility and contrast.Map: Strebe, using the Geocart map projection software
This image represents a view from the "front" of the neural system of a giant scallop, slightly turned, with the shell or "valve" hinge line at the top and open free margin along the bottom (this image shows what most observers might think of as a "side view" or "edge view"— see inset for orientation). The largest, most important ganglia are the parietovisceral (not the cerebral) which connect to the circumpallial nerve somewhat like an axle connects via spokes to the rim of a wheel. The circumpallial nerve forms a complete folded double ring around the edge of the animal's disk-like mantle inside each valve (mantle not shown here). The hundreds of nerves of the scallop's eyes and tentacles would have appeared as long thin lines jutting off along the entire length of this nerve like hazy fringe.Diagram: K.D. Schroeder