Oferta Y Demanda

1. Other molecules enveloping a planet, such as oxygen, ozone and methane, can suggest that life itself has taken root. On Earth, oxygen is "breathed out" by plants, and methane by micro-creatures living in swamps and animals. These chemicals don't stick around for long on their own, so if they are hanging around an extrasolar planet, then something must be pumping the stuff out. That something could be life, but this isn't always the case. Saturn's moon's Titan is shrouded in an atmosphere containing lots of methane not produced by life.

2. The energy source that creates the aurora originates from the solar wind, an electrically charged gas (plasma) released by the sun that impacts the Earth's magnetic field. This energy ultimately sets up electric fields in space that accelerate electrically charged particles trapped in the Earth's magnetic field. The particles slam into the upper atmosphere above the polar regions, generating the dynamic and beautiful glow we know as the aurora.

3. Scientists say that oxygen is a more reliable sign of life than methane, but if they found large quantities of both, they'd be more convinced. "Finding two of these molecules together would be much better than one. The more, the better," said Dr. Victoria Meadows of NASA's Spitzer Science Center, Pasadena, who served as chair of the third Pale Blue Dot conference. "For example, if we found carbon dioxide, oxygen and water vapor, in addition to methane, then we'd be pretty convinced that we were looking at an environment like our own."

Taken from: http://education.nasa.gov/home/index.html

4. This account of the making of the Great Pyramid, although rich and coherent, does not satisfy everyone, and there are many who persist in attributing the Great Pyramid to some agency outside the human race. There is a whole branch of the publishing industry devoted to meeting this hunger for pyramidical mysteries, which is sharpened by movies such as Stargate and The Fifth Element, and shows no sign of tapering off in the 21st century.

This accumulation of fringe beliefs is sometimes known as 'pyramidology'; some of its major tendencies are described here, with catch-all names for the sake of brevity…..

5. To understand the Vikings as a ‘people’ 19th-century historian turned to the written evidence of sagas and chronicles. However, the documents don't tell the whole story, as Gareth Williams explains…….

Taken from: http://en.wikipedia.org/wiki/Wikijunior

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