User:M&NCenarius/3 (2007)

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May to June 2007
The featured things
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<<March to April ' 07

[edit] Global Warming

April 30 - May 6

Global warming is the increase in the average temperature of the Earth's atmosphere and oceans that has been observed in recent decades. The scientific opinion on climate change is that much of the recent change may be attributed to human activities. Carbon dioxide and other greenhouse gases released by the burning of fossil fuels, land clearing, agriculture, among other human activities, are the primary sources of the human-induced component of warming. Observational sensitivity studies and climate models referenced by the IPCC predict that global temperatures may increase by between 1.4 and 5.8 °C between 1990 and 2100. An increase in global temperatures can in turn cause other changes, including rises in sea level and changes in the amount and pattern of precipitation. These changes may increase the frequency and intensity of extreme weather events, such as tropical cyclones or floods. There are a few scientists who contest the view about attribution of recent warming to human activity. Uncertainties exist regarding how much climate change should be expected in the future, and there is a hotly contested political and public debate over attempts to reduce or reverse future warming, and how to cope with possible consequences.

Recently featured: Buddhism: Sense of Reason - Orca - Velociraptor

[edit] Galaxy

May 7 - May 13

A galaxy is a massive, gravitationally bound system that consists of stars, an interstellar medium of gas and dust, and dark matter. Typical galaxies range from dwarfs with as few as ten million (10⁷) stars up to giants with one trillion (10¹²) stars, all orbiting a common center of gravity. Galaxies can also contain a large number of multiple star systems and star clusters as well as various types of interstellar clouds. Historically, galaxies have been categorized according to their apparent shape. Interactions between nearby galaxies, which may ultimately result in a galaxy merger, may induce episodes of significantly increased star formation, producing what is called a starburst galaxy. There are probably more than a hundred billion (10¹¹) galaxies in the observable universe. Most galaxies are a thousand to a hundred thousand parsecs in diameter and are usually separated from one another by distances on the order of millions of parsecs. Intergalactic space, the space between galaxies, is filled with a tenuous gas with an average density less than one atom per cubic metre. There is some evidence that supermassive black holes may exist at the center of many, if not all, galaxies. These massive objects are believed to be the primary cause of active galactic nuclei found at the core of some galaxies. The Milky Way galaxy appears to harbor at least one such object within its nucleus.

Recently featured: Global warming - Buddhism: Sense of Reason - Orca

to be continued

>>July to August ' 07

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