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Nov 7, 2006
Surface of the Earth, colors reflect changes in elevationThe Earth's terrain varies greatly from place to place. About 70% of the surface is covered by water, with much of the continental shelf below sea level. If all of the land on Earth were spread evenly, water would rise to an altitude of more than 2500 metres. The remaining 30% not covered by water consists of mountains, deserts, plains, plateaus, etc. Currently the total arable land is 13.31% of the land surface, with only 4.71% supporting permanent crops. Close to 40% of the Earth's land surface is presently used for cropland and pasture, or an estimated 3.3 × 109 acres of cropland and 8.4 × 109 acres of pastureland.
Posted at 10:47 am by veerpandi
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Oct 23, 2006
Very few galaxies exist by themselves; these are known as field galaxies. Most galaxies are gravitationally bound to a number of other galaxies. Structures containing up to about 50 galaxies are called groups of galaxies, and larger structures containing many thousands of galaxies packed into an area a few megaparsecs across are called clusters. Clusters of galaxies are often dominated by a single giant elliptical galaxy, which over time tidally destroys its satellite galaxies and adds their mass to its own. Superclusters are giant collections containing tens of thousands of galaxies, found in clusters, groups and sometimes individually; at the supercluster scale, galaxies are arranged into sheets and filaments surrounding vast empty voids. Above this scale, the universe appears to be isotropic and homogeneous. Our galaxy is a member of the Local Group, which it dominates together with the Andromeda Galaxy; overall the Local Group contains about thirty galaxies in a space about one megaparsec across. The Local Group is part of the Virgo Supercluster, which is dominated by the Virgo Cluster.
Posted at 04:17 am by veerpandi
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Oct 4, 2006
Pawpaw also recognized as a prairie banana, Kentucky banana, or Ozark banana, is a genus of eight or nine class of small trees with large leaves and fruit, native to southeastern North America. The genus includes the main edible fruit native to North America. They are understorey trees of yawning fertile bottomland soils. The name, also spelled paw paw, paw-paw, and papaw, most likely derives from the Spanish papaya, perhaps due to the superficial resemblance of their fruit. Pawpaw is in the same family Annunciate as the custard-apple, soursop, sweetsop, and cherimoya, and it is the only associate of that family not confined to the tropics.
The pawpaws are undergrowth or small trees, reaching heights of 2 to 12 m tall. The leaves are alternate, easy ovate, entire, 20 to 35 cm long and 10 to 15 cm broad. The northern, cold tolerant common pawpaw is deciduous, while the southern varieties are often evergreen. The fetid flowers are shaped singly or in clusters of up to eight together; they are large, 4 to 6 cm across, ideal, with six sepals and petals. The petal color varies from white to purple or red-brown. Pollinated by scavenging carrion flies and beetles, the flowers produce a weak scent which attracts few pollinators, thus limiting fruit construction. Larger growers sometimes locate rotting meat near the trees at bloom time to increase the number of blowflies. Asimina triloba is the single larval host of the Zebra Swallowtail Butterfly.
Posted at 06:21 pm by veerpandi
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Sep 26, 2006
An earthquake is a phenomenon that results from and is powered by the sudden release of stored energy that radiates seismic waves. At the Earth's surface,
earthquakes may manifest themselves by a shaking or displacement of the ground and sometimes tsunamis, which may lead to loss of life and destruction of
property.
Earthquakes may occur naturally or as a result of human activities. In its most generic sense, the word earthquake is used to describe any seismic
event—whether a natural phenomenon or an event caused by humans—that generates seismic waves.
Earthquakes occur on a daily basis around the world, most detected only by seismometers and causing no damage. Large earthquakes however can cause
serious destruction and massive loss of life through a variety of agents of damage, including fault rupture, vibratory ground motion, inundation, various kinds
of permanent ground failure, and fire or a release of hazardous materials e.g gas leaks or petrol leaks. In a particular earthquake, any of these agents of
damage can dominate, and historically each has caused major damage and great loss of life; nonetheless, for most earthquakes shaking is the dominant
and most widespread cause of damage. There are four types of seismic waves that are all generated simultaneously and can be felt on the ground.
Responsible for the shaking hazard, they are P-waves, S-waves and two types of surfaces waves.
Posted at 06:47 am by veerpandi
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Aug 28, 2006
The Red Kite:
Also known as Milvus is a medium-large bird of prey in the
family Accipitridae, which also includes many other diurnal raptors such as eagles,
buzzards and harriers. It is a European rare species which is resident in the
milder parts of its range, but birds from northern and central Europe
winter further south and west. It is 61–72 cm long with a 175-200 cm wingspan.
It is an elegant bird, soaring with long wings held at a dihedral, and long
forked tail twisting as it changes direction. The call is a thin piping,
similar to but less mewling than Common Buzzard. This species nests in trees,
often close to other kites. In winter, many kites will roost together.
Posted at 04:35 am by veerpandi
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Jul 21, 2006
Redstockings, also recognized as Redstockings of the Women's freedom Movement, is a radical feminist assembly that was mainly active during the 1970s. The term is a neologism, combining the term bluestocking, a perjoritive term for intellectual women, with "red", for its relationship with the revolutionary left.
Posted at 10:58 pm by veerpandi
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