Tree

A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance.[1] A minimum height specification at maturity is cited by some authors, varying from 3 m[2] to 6 m;[3] some authors set a minimum of 10 cm trunk diameter (30 cm girth).[4] Woody plants that do not meet these definitions by having multiple stems and/or small size, are called shrubs. Compared with most other plants, trees are long-lived, some reaching several thousand years old and growing to up to 115 m (379 ft) high.[5]

Trees are an important component of the natural landscape because of their prevention of erosion and the provision of a weather-sheltered ecosystem in and under their foliage. Trees also play an important role in producing oxygen and reducing carbon dioxide in the atmosphere, as well as moderating ground temperatures. They are also elements in landscaping and agriculture, both for their aesthetic appeal and their orchard crops (such as apples). Wood from trees is a building material, as well as a primary energy source in many developing countries. Trees also play a role in many of the world's mythologies (see trees in mythology). 

A tree is a plant form that occurs in many different orders and families of plants. Trees show a variety of growth forms, leaf type and shape, bark characteristics, and reproductive organs. The tree form has evolved separately in unrelated classes of plants, in response to similar environmental challenges, making it a classic example of parallel evolution. With an estimate of 100,000 tree species, the number of tree species worldwide might total 25 percent of all living plant species.[7] The majority of tree species grow in tropical regions of the world and many of these areas have not been surveyed yet by botanists, making species diversity and ranges poorly understood.[8]

The earliest trees were tree ferns, horsetails and lycophytes, which grew in forests in the Carboniferous Period; tree ferns still survive, but the only surviving horsetails and lycophytes are not of tree form. Later, in the Triassic Period, conifers, ginkgos, cycads and other gymnosperms appeared, and subsequently flowering plants in the Cretaceous Period. Most species of trees today are flowering plants (Angiosperms) and conifers. For the listing of examples of well-known trees and how they are classified, see List of tree genera.

Plants

Plants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. About 350,000 species of plants, defined as seed plants, bryophytes, ferns and fern allies, are estimated to exist currently. As of 2004, some 287,655 species had been identified, of which 258,650 are flowering and 18,000 bryophytes (see table below). Green plants, sometimes called metaphytes or viridiplantae, obtain most of their energy from sunlight via a process called photosynthesis.

Aristotle divided all living things between plants (which generally do not move), and animals (which often are mobile to catch their food). In Linnaeus' system, these became the Kingdoms Vegetabilia (later Metaphyta or Plantae) and Animalia (also called Metazoa). Since then, it has become clear that the Plantae as originally defined included several unrelated groups, and the fungi and several groups of algae were removed to new kingdoms. However, these are still often considered plants in many contexts, both technical and popular.

When the name Plantae or plants is applied to a specific taxon, it is usually referring to one of three concepts. From smallest to largest in inclusiveness, these three groupings are: Informally, other creatures that carry out photosynthesis are called plants as well, but they do not constitute a formal taxon and represent species that are not closely related to true plants. There are around 375,000 species of plants, and each year more are found and described by science.

Most algae are no longer classified within the Kingdom Plantae.[2][3] The algae comprise several different groups of organisms that produce energy through photosynthesis, each of which arose independently from separate non-photosynthetic ancestors. Most conspicuous among the algae are the seaweeds, multicellular algae that may roughly resemble terrestrial plants, but are classified among the green, red, and brown algae. Each of these algal groups also includes various microscopic and single-celled organisms.

Musical instrument

A musical instrument is a device constructed or modified for the purpose of making music. In principle, anything that produces sound can serve as a musical instrument. The term "musical instrument", however, is generally reserved for items that have a specific musical purpose such as a piano. The academic study of musical instruments is called organology.

Scholars agree that there are no completely reliable methods of determining the exact chronology of musical instruments across cultures. Comparing and organizing instruments based on their complexity is misleading, since advancements in musical instruments have sometimes reduced complexity. For example, construction of early slit drums involved felling and hollowing out large trees; later slit drums were made by opening bamboo stalks, a much simpler task.[1] It is likewise misleading to arrange the development of musical instruments by workmanship since all cultures advance at different levels and have access to different materials. For example, anthropologists attempting to compare musical instruments made by two cultures that existed at the same time but who differed in organization, culture, and handicraft cannot determine which instruments are more "primitive".[2] Ordering instruments by geography is also partially unreliable, as one cannot determine when and how cultures contacted one another and shared knowledge. German musicologist Curt Sachs, one of the most prominent musicologists in modern times,[3] proposed that a geographical chronology is preferable, however, due to its limited subjectivity.[4]

Archaeological evidence of musical instruments was discovered in excavations at the Royal Cemetery in the Sumerian city of Ur. These instruments include nine lyres, two harps, a silver double flute, sistra and cymbals. These excavations, carried out by Leonard Woolley in the 1920s, uncovered non-degradable fragments of instruments and the voids left by the degraded segments which, together, have been used to reconstruct them.[5] The graves to which these instruments were related have been carbon dated to between 2600 and 2500 BCE, providing evidence that these instruments were being used in Sumeria by this time.[6]

A cuneiform tablet from Nippur in Mesopotamia dated to 2000 BCE indicates the names of strings on the lyre and represents the earliest known example of music notation.[7] Until the 19th century AD, written music histories began with mythological accounts of how musical instruments were invented. Such accounts included Jubal, descendant of Cain and "father of all such as handle the harp and the organ", musical instrument" is completely subjective to both the scholar and the would-be inventor. For example, a Homo habilis slapping his body could be the makings of a musical instrument regardless of the being's intent. 

Toy

A toy is an object used in play. Toys are usually associated with children and pets, but it is not unusual for adult humans and some non-domesticated animals to play with toys. Many items are manufactured to serve as toys, but items produced for other purposes can also be used as toys. A child may pick up a household item and 'fly' it around pretending that it is an airplane, or an animal might play with a pinecone by batting at it, biting it, chasing it, or by throwing it up in the air. Some toys are produced primarily as collector's items and are not intended to be played with.

The origin of toys is prehistoric; dolls representing infants, animals, and soldiers, as well as representations of tools used by adults are readily found at archaeological sites. The origin of the word "toy" is unknown, but it is believed that it was first used in the 14th century.[1] Toys, and play in general, are important when it comes to growing up and learning about the world around us. The young use toys and play to discover their identity, help their bodies grow strong, learn cause and effect, explore relationships, and practice skills they will need as adults. Adults use toys and play to form and strengthen social bonds, teach, remember and reinforce lessons from their youth, discover their identity, exercise their minds and bodies, explore relationships, practice skills, and decorate their living spaces.

Toys are more than simple amusement, they and the ways that they are used profoundly influence many aspects of life.[ Most young mammals will play with whatever they can find, turning such things as pinecones, rocks, and food into toys. It simply makes sense then that toys have a history as old as human civilization itself. Toys and games have been unearthed from the sites of ancient civilizations. They have been written about in some of our oldest literature. Toys excavated from the Indus valley civilization (3000-1500 BCE) include small carts, whistles shaped like birds, and toy monkeys which could slide down a string.[2]

The earliest toys were made from materials found in nature, such as rocks, sticks, and clay. Thousands of years ago, Egyptian children played with dolls that had wigs and movable limbs which were made from stone, pottery, and wood.[3] In Ancient Greece and Ancient Rome, children played with dolls made of wax or terra cotta, sticks, bows and arrows, and yo-yos. When Greek children, especially girls, came of age it was customary for them to sacrifice the toys of their childhood to the gods. On the eve of their wedding, young girls around fourteen would offer their dolls in a temple as a rite of passage into adulthood.[4][5]

Art

Art is the process or product of deliberately arranging elements in a way that appeals to the sense or emotions. Art encompasses a diverse range of human activities, creations, and modes of expression, including music and literature. Aesthetics is the branch of philosophy which studies art. Traditionally, the term art was used to refer to any skill or mastery. This conception changed during the Romantic period, when art came to be seen as "a special faculty of the human mind to be classified with religion and science".[1] Generally art is made with the intention of stimulating thoughts and emotions.

Visual art is defined as the arrangement of colors, forms, or other elements "in a manner that affects the sense of beauty, specifically the production of the beautiful in a graphic or plastic medium".[2] The nature of art has been described by Wollheim as "one of the most elusive of the traditional problems of human culture".[3] The most common usage of the word "art," which rose to prominence after 1750, is understood to denote skill used to produce an aesthetic result.[7] Britannica Online defines it as "the use of skill and imagination in the creation of aesthetic objects, environments, or experiences that can be shared with others."[8] 

By any of these definitions of the word, artistic works have existed for almost as long as humankind: from early pre-historic art to contemporary art; however, some theories restrict the concept to modern Western societies.[9] Much has been written about the concept of "art".[10] Where Adorno said in 1970 "It is now taken for granted that nothing which concerns art can be taken for granted any more[...],"[11],[12] The first and broadest sense of art is the one that has remained closest to the older Latin meaning, which roughly translates to "skill" or "craft," and also from an Indo-European root meaning "arrangement" or "to arrange". 

The second and more recent sense of the word art is as an abbreviation for creative art or fine art. Fine art means that a skill is being used to express the artist’s creativity, or to engage the audience’s aesthetic sensibilities, or to draw the audience towards consideration of the finer things. Often, if the skill is being used in a common or practical way, people will consider it a craft instead of art. Likewise, if the skill is being used in a commercial or industrial way, it will be considered Commercial art instead of fine art. On the other hand, crafts and design are sometimes considered applied art. Some art followers have argued that the difference between fine art and applied art has more to do with value judgments made about the art than any clear definitional difference.[13] However, even fine art often has goals beyond pure creativity and self-expression. sense of beauty (see aesthetics); to explore the nature of perception; for pleasure; or to generate strong emotions. The purpose may also be seemingly nonexistent.

Animation

Animation is the rapid display of a sequence of images of 2-D or 3-D artwork or model positions in order to create an illusion of movement. It is an optical illusion of motion due to the phenomenon of persistence of vision, and can be created and demonstrated in a number of ways. The most common method of presenting animation is as a motion picture or video program, although several other forms of presenting animation also exist.

Early examples of attempts to capture the phenomenon of motion drawing can be found in paleolithic cave paintings, where animals are depicted with multiple legs in superimposed positions, clearly attempting to convey the perception of motion. A 5,200 year old earthen bowl found in Iran in Shahr-i Sokhta has five images of a goat painted along the sides.This has been claimed to be an example of early animation.[1][2][3] However, since no equipment existed to show the images in motion, such a series of images cannot be called animation in a true sense of the word.[4][5]

The phenakistoscope, praxinoscope, as well as the common flip book were early popular animation devices invented during the 1800s, while a Chinese zoetrope-type device was invented already in 180 AD.[6][7][8][9] These devices produced movement from sequential drawings using technological means, but animation did not really develop much further until the advent of cinematography. There is no single person who can be considered the "creator" of the art of film animation, as there were several people doing several projects which could be considered various types of animation all around the same time.

Georges Méliès was a creator of special-effect films; he was generally one of the first people to use animation with his technique. He discovered a technique by accident which was to stop the camera rolling to change something in the scene, and then continue rolling the film. This idea was later known as stop-motion animation. Méliès discovered this technique accidentally when his camera broke down while shooting a bus driving by. When he had fixed the camera, a hearse happened to be passing by just as Méliès restarted rolling the film, his end result was that he had managed to make a bus transform into a hearse. This was just one of the great contributors to animation in the early years.

Sun

The Sun (Latin: Sol), a yellow dwarf, is the star at the center of the Solar System. The Earth and other matter (including other planets, asteroids, meteoroids, comets, and dust) orbit the Sun,[9] which by itself accounts for about 99.8% of the Solar System's mass. The mean distance of the Sun from the Earth is approximately 149,600,000 kilometers, or 92,960,000 miles, and its light travels this distance in 8.3 minutes. Energy from the Sun, in the form of sunlight, supports almost all life on Earth via photosynthesis, and drives the Earth's climate and weather.

The surface of the Sun consists of hydrogen (about 74% of its mass, or 92% of its volume), helium (about 24% of mass, 7% of volume), and trace quantities of other elements, including iron, nickel, oxygen, silicon, sulfur, magnesium, carbon, neon, calcium, and chromium.[10] The Sun has a spectral class of G2V. G2 means that it has a surface temperature of approximately 5,780 K (5,500 C) giving it a white color that often, because of atmospheric scattering, appears yellow when seen from the surface of the Earth. This is a subtractive effect, as the preferential scattering of shorter wavelength light removes enough violet and blue light, leaving a range of frequencies that is perceived by the human eye as yellow. It is this scattering of light at the blue end of the spectrum that gives the surrounding sky its color. When the Sun is low in the sky, even more light is scattered so that the Sun appears orange or even red.[11]

The Sun's spectrum contains lines of ionized and neutral metals as well as very weak hydrogen lines. The V (Roman five) in the spectral class indicates that the Sun, like most stars, is a main sequence star. This means that it generates its energy by nuclear fusion of hydrogen nuclei into helium. There are more than 100 million G2 class stars in our galaxy. Once regarded as a small and relatively insignificant star, the Sun is now known to be brighter than 85% of the stars in the galaxy, most of which are red dwarfs.[12]

The Sun orbits the center of the Milky Way galaxy at a distance of approximately 24,000 to 26,000 light years from the galactic center, moving generally in the direction of Cygnus and completing one revolution in about 225–250 million years (one Galactic year). Its orbital speed was thought to be 220±20 km/s, but a new estimate gives 251 km/s[13]. This is equivalent to about one light-year every 1,190 years, and about one AU every 7 days. These measurements of galactic distance and speed are as accurate as we can get given our current knowledge, but may change as we learn more.[14] Since our galaxy is moving with respect to the cosmic microwave background radiation (CMB) in the direction of Hydra with a speed of 550 km/s, the sun's resultant velocity with respect to the CMB is about 370 km/s in the direction of Crater or Leo.[15]