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A freeway is a multi-lane highway (road) designed for high-speed travel by large numbers of vehicles, and having no traffic lights, stop signs, nor other regulations requiring vehicles to stop for cross-traffic.

Interstate 80 is a major urban freeway through the East Bay, north of the Bay Bridge, in the San Francisco Bay Area (seen here in Berkeley, California).

Photo credit: Minesweeper
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The Matterhorn is located on the border between Switzerland and Italy, towering over the Swiss town of Zermatt and the Italian town Breuil-Cervinia in the Val Tournanche. Long an iconic symbol of Switzerland and the Alps, it was the last major mountain of the range to be climbed, not merely because of its technical difficulty, but of the fear it inspired in early mountaineers. The summit of the Matterhorn was first reached in 1865, after several years of attempts. By today's standards, the climbing is not especially hard, and thousands make the ascent each summer.

Photo credit: Stan Shebs
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Segovia is a city in Spain, the capital of the province of Segovia in Castile-Leon. It is situated about an hour north of Madrid. The old city is a UNESCO World Heritage Site and has the highest concentration of Romanesque churches in Europe. It is also noted for its 16th century Gothic cathedral (shown here), its Roman aqueduct and fairy-tale castle, or Alcázar.

Photo credit: Óscar Ibáñez Fernández
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The Taj Mahal in Agra, India, was commissioned by the 17th century Mughal Emperor Shah Jahan, as a mausoleum for his Persian wife, Mumtaz Mahal. Built over a period of 23 years, it is a masterpiece of Mughal architecture, featuring the finest materials from all over India and Asia. Its gleaming facade is clad in white marble from Rajasthan and inlaid with 28 types of precious and semi-precious stones. It is a UNESCO World Heritage Site considered to be of "outstanding universal value".

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The Cathedral of Magdeburg is the first gothic cathedral in Germany and with a height of 104 m the highest cathedral in Eastern Germany. The current cathedral was constructed over the period of 300 years starting from 1209, and the completion of the steeples took place only in 1520. Despite being repeatedly looted, the Cathedral is rich in art, ranging from antiques to modern art.

Photo credit: Chris 73
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Dandelion (Taraxacum) is a large genus of flowering plants in the family Asteraceae. They are tap-rooted biennial or perennial herbaceous plants, native to temperate areas of the Northern Hemisphere and also temperate southern South America. The genus is taxonomically very complex, with numerous apomictic microspecies, and polyploidy is also common; over 250 species have been recorded in the British Isles alone. Some botanists take a much broader viewpoint, and only accept a total of about 60 species.

Photo credit: Markus Bernet
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Strelitzia is a South African genus of perennial plants named after the duchy of Mecklenburg-Strelitz, home of the former Queen Charlotte of England. The common name of the genus is "bird of paradise", because of the resemblance of its flowers to the bird of that name.

Photo credit: Scott Bauer USDA
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The US Federal Government controls a 6000 mi² tract of southern Nevada, including the Nellis Air Force Range and the Nevada Test Site. These contain the Yucca Mountain repository, the Tonopah Test Range, and the secret Area 51 facility.

Illustration credit: Finlay McWalter
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An image of Pollen taken by a Scanning Electron Microscope (SEM), a type of electron microscope capable of producing high resolution images of a sample surface. Due to the manner in which the image is created, SEM images have a characteristic 3-dimensional quality and are useful for judging the surface structure of the sample.

Photo credit: Rippel Electron Microscope Facility
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Biological dispersal refers to those processes by which a species maintains or expands the distribution of a population. For non-aquatic, terrestrial plants, the wind is an obvious supplier of energy of movement, and many plant adaptations exist that clearly take advantage of this fact. Perhaps most familiar are the feather-light fibre parachutes with attached achenes that are produced by a number of species of Asteraceae, a well-known example being the dandelion.

Photo credit: PiccoloNamek
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Pollination is an important step in the reproduction of seed plants: the transfer of pollen grains (male gametes) to the plant carpel, the structure that contains the ovule (female gamete). Pollination by insects, or entomophily, is a common pollination strategy. Here a wild Melissodedes bee crawls among the stamens of a rose collecting pollen on its hindlegs. The female reproductive organ of the rose (the pistil) can be seen as the globular rough-surfaced structure to the left of the bee; it is surrounded by dozens of pollen-bearing stamens.

Photo credit: Debivort
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The Bald Eagle is a raptor that is indigenous to North America, and is the national symbol of the United States of America. The species was on the brink of extinction late in the 20th century but has largely recovered and now has a stable population. Its diet is varied, including fish, smaller birds, rodents, and sometimes food scavenged or stolen from campsites and picnics.

Photo credit: Adrian Pingstone
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The order Mantodea (or Praying mantis) consists of between 1,800 and 2,000 species, of which a majority are in Mantidae.

Mantids are notable for their large size and nimble reflexes. They are masters of camouflage and make use of protective coloration to blend in with the foliage, both to avoid predators themselves, and to better snare their victims. Some species in Africa and Australia are able to turn black within a few days of a fire in the region to blend in with the fire ravaged landscape.

Photo credit: PiccoloNamek
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The American White Ibis is a species of wading bird of the ibis family, indigenous to the southern USA and the Caribbean. It lives in marshy wetlands, and on beaches, and has become common in city parks. They build a stick nest in a tree or bush over water, and 2-5 eggs are laid. This ibis feeds on various fish, frogs and other water creatures, and also insects. Adults are 65 cm long with a 95 cm wingspan. They are all-white except for black wing-tips and red bills and legs. Juveniles are largely brown with duller bare parts.

Photo credit: Jaap Folmer
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The American Burying Beetle, or Giant Carrion Beetle, is an endangered species of beetle endemic to North America. It is the largest carrion beetle in North America, is carnivorous, feeds on carrion and requires carrion to breed. It is also one of the few species of beetle to exhibit parental care. The decline of the American burying beetle has been attributed to habitat loss, alteration, and degradation, and they now occur over less than 10% of their historic range.

Photo credit: U.S. Fish and Wildlife Service
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An optical illusion is any illusion that deceives the human visual system into perceiving something that is not present or incorrectly perceiving what is present. There are physiological illusions and cognitive illusions. A mirage is an example of a natural illusion that is an optical phenomenon, another example is the variation in the apparent size of the Moon (smaller when overhead, larger when near the horizon), this is not an optical phenomenon, but rather a cognitive or perceptual illusion.

Photo credit: Edward H. Adelson
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The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the opening into the San Francisco Bay from the Pacific Ocean. The entire bridge including the approach spans is 1.7 miles (2727 m) long, whilst the main span between the towers is 4200 feet (1280 m). The two towers rise 746 feet (230 m) above the water. From its completion in 1937, the center span was the longest among suspension bridges until 1964 when the Verrazano Narrows Bridge was erected.

Photo credit: Daniel Schwen
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The lavenders are 25 to 30 species of flowering plants in the genus Lavandula and the family Lamiaceae (mints) native to regions from the Mediterranean south to tropical Africa and east to India. Lavenders are widely grown in gardens. The fragrant, pale purple flowers and flower buds are used in potpourris. The plant is also grown commercially for extraction of lavender oil from the flowers. This oil is used as an antiseptic and for aromatherapy. Photo credit: Fir0002
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The Very Large Array is a radio astronomy observatory that consists of 27 independently movable radio antennae, each of which has a dish diameter of 25 meters and weighs 230 tons. There are four commonly used configurations, designated A (the largest, when the furthest dishes are 36 km apart) through D (the tightest, when all 27 are within 600 m of the center point).

Photo credit: Hajor
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In 1965, as the Vietnam War escalated, the United States committed some 125,000 troops to support the southern Republic of Vietnam. Here a young Marine private waits on the beach during the troop landings at Da Nang, Vietnam on August 3, 1965.

Photo credit: Unknown - NARA archive
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The 1917 Battle of Passchendaele, also known as the Third Battle of Ypres, was one of the major battles of World War I, fought by British, ANZAC, and Canadian soldiers against the German army. The battle was fought for control of the village of Passendale, (Belgium-French Passchendaele on maps of that time), near the Belgian town of Ypres in West Flanders.

These before and after aerial photographs, show the effect of the extensive bombardment during the battle.

Photo credit: Imperial War Museum
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Hornets are large eusocial wasps. The true hornets make up the genus Vespa, and are distinguished from other vespids by the width of the vertex (part of the head behind the eyes), which is proportionally larger in Vespa; and by the anteriorly rounded gasters (the section of the abdomen behind the wasp waist).

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Water colored red by Iron. Iron comprises 95 percent of all the metal tonnage produced worldwide. Its combination of low cost and high strength make it indispensable, especially in applications like automobiles, the hulls of large ships, and structural components for buildings. The first signs of use of iron come from the Sumerians and the Egyptians, where around 4000 BC, small items were being fashioned from iron recovered from meteorites.

Photo credit: NASA
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SN 1572, or Tycho's Nova, was a supernova in the constellation Cassiopeia, one of the few supernovae visible by the naked eye. It was first observed on November 11, 1572 by Tycho Brahe, when it was brighter than Venus.

This is a false-colour x-ray image from the Chandra X-ray Observatory in which the energy levels of the x-rays have been assigned red, green and blue colors in three bands from 0.95 keV to 6.1 keV. The red and green bands highlight the expanding cloud of plasma with temperatures in the millions of degrees. The blue band shows a surrounding shell of extremely high energy electrons.

Photo credit: NASA/CXC/Rutgers/
J.Warren & J.Hughes et al.
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Pillar corals are a type of hard coral which live in the western Atlantic Ocean. They are one of the digitate corals which resemble fingers, or a cluster of cigars growing up from the sea floor, but without any secondary branching. Pillar corals can grow to be up to 2.5 m (8 ft) tall. They can grow on both flat and sloping sea floors at a depth of between 1 and 20 m (65 ft). They are one of the few types of hard coral whose polyps can commonly be seen feeding during the day.

Photo credit: NOAA
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Hay is dried grass typically stored to feed domestic animals in winter when not enough fresh grass is available. It is normally produced by allowing excess pasture paddocks to grow, then just before the grasses flower the pasture is mowed and the cut grass allowed to dry in the sun for two or three days.

Traditional thatched haystacks, seen here in Romania, store the dried hay and protect it from rain until needed. In the 20th century these have largely been replaced by mechanical balers, that gather and compact the hay into rectangular or rolled bales for easier storage.

Photo credit: Paulnasca
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Pollen, like on this Gerbera, is a fine powder consisting of pollen grains, which carry the male gametes of seed plants. The transfer of pollen grains to the female reproductive structure can be mediated by the wind, in which case the plant is described as wind-loving, these plants typically produce great quantities of very lightweight pollen grains. Insect-loving plants produce pollen that is relatively heavy and sticky, for dispersal by insect pollinators attracted to their flowers.

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Photo credit: Alan Mak
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The London Millennium Footbridge, opened on June 10, 2000, was a Millennium Project designed by Foster and Partners with Sir Anthony Caro. It is the first new bridge across the Thames in London since Tower Bridge in 1894.

On its opening day the bridge exhibited alarmingly large lateral vibrations. The initial small sideways movements encouraged pedestrians to walk in synchronisation with the sway, which forced the motion to uncomfortable levels. As a result the bridge was swiftly nicknamed the Wobbly Bridge. Two days later the bridge was closed to retrofit dampers to correct the problem.

Photo credit: Paul Lomax
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Winter is one of the four seasons of temperate zones. Meteorological winter is the season having the shortest days (which vary greatly according to latitude) and the lowest temperatures.

During winter, there is much snow and cold, especially in areas that are farther away from the Equator. Blizzards often develop and cause many delays. A rare meteorological phenomenon encountered during winter is ice fog, which is composed of ice crystals suspended in the air and occurs only at very low temperatures (at least 10 degrees below zero).

Photo credit: Richard Fabi
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