High-purity niobium crystals, with a 1 cm³ cube of anodized niobium for comparison. Niobium is a soft, grey, ductile transition metal named after Niobe from Greek mythology. Niobium is typically used in steel alloys; only a tiny amount (0.1%) is required to improve the strength of the steel.

Photo: Alchemist-hp

The Black Kite (Milvus migrans) is a medium-sized bird of prey easily identifiable by its angled wing and distinctive forked tail. It is widely distributed through the temperate and tropical parts of Eurasia and parts of Australasia and Oceania, with the temperate region populations tending to be migratory.

Photo: Benjamint444

The Pink Lady's Slipper (Cypripedium acaule) is an orchid native to eastern North America. This widespread species can be found in a wide variety of environments, from coastal plains, to pine barrens, to mountaintops. It is the provincial flower of Prince Edward Island, Canada.

Photo: Sasata

The violet coral (Clavaria zollingeri) is a widely distributed species of fungus with tubular, purple basidiocarps (fruit bodies) that grow in clusters up to 10 cm (3.9 in) tall and 7 cm (2.8 in) wide. It is a saprobic species, growing on the ground in woodland litter.

Photo: Dan Molter

The aurora australis, as seen from the International Space Station. Aurorae are natural light displays in the sky caused by the collision of energetic charged particles with atoms in the high altitude thermosphere. The particles originate in the magnetosphere and solar wind and, on Earth, are directed by Earth's magnetic field into the atmosphere.

Photo: NASA/ISS Expedition 23 crew

Successive close-ups of the scales of a Peacock butterfly (at top) wing. Shown from left to right, top to bottom: (second row) a closeup of the scales of the specimen at top, high magnification view of coloured scales (different species); (third row) electron micrograph of a patch of wing (~×50 magnification), the scales close up (~×200); (last row) a single scale (×1000), microstructure of a scale (×5000).

Photos: MichaD (top and second row left), Shaddack (second row right), SecretDisc (micrographs)

The Wave (1896) by William-Adolphe Bouguereau, an example of an art nude, an art form where the naked human form is the dominant theme and is not intentionally erotic. It does not involve the subject interacting with anyone or the face of the nude as a prominent feature. The body presented is revealed as an object of art and not a person with reference to his or her social relationships and behavioral patterns.

An odd-eyed cat is a cat with one blue eye and one green, yellow, or brown eye. This is a feline form of complete heterochromia, a condition also present in humans and some other animals (including horses and huskies). It can occur in a cat of any fur color, provided that it possesses the white spotting gene. Animals affected by the condition can have partial heterochromia, in which only part of the iris is a different color.

Photo: Keith Kissel

A panoramic view of Brandenburg an der Havel, a town in the state of Brandenburg, Germany, located on the banks of the River Havel. The town was founded by the Hevelli, a tribe of Polabian Slavs, in the 8th century, and changed hands between Germans and Slavs several times. Development was restricted to the western bank of the Havel until 1196, when it was extended to the eastern side, although the two portions were regarded as separate towns until 1715.

Photo: Mathias Krumbholz

A male Dendropsophus microcephalus frog, displaying its vocal sac—membranes of skin under the throat or on the corner of the mouth that distend to amplify its call. The species lives in moist areas in most of Central America and northern South America.

Photo: Brian Gratwicke

A romanticized depiction of a tramp smoking a cigar with a cane over his arm, from an 1899 poster. A tramp is a homeless person who travels from place to place as a vagrant, traditionally on foot. Unlike other temporarily homeless people, they do not seek out regular work and support themselves by other means such as begging or scavenging. The term "tramp" is derived from the Middle English as a verb meaning to "walk with heavy footsteps" (cf. the modern English word "trample").

Image: United States Printing Company; Restoration: Adam Cuerden