Wednesday, February 10, 2010

BBC - THE SUN: PART 2-A (Star Stuff)




The Sun is a 1 million km wide ball of burning gas. So be prepared for the best firework show you have ever seen! Solar flares - Variations in the Suns magnetic field cause huge jets or loops of stellar material to shoot out into space. Solar wind - Solar flares can be accompanied by dense clouds of electrically charged particles, travelling at around 450km per second. When they reach Earth, they can affect communications satellites.

A BBC DOCUMENTARY:


The Sun is a 1 million km wide ball of burning gas. So be prepared for the best firework show you have ever seen! Solar flares - Variations in the Suns magnetic field cause huge jets or loops of stellar material to shoot out into space. Solar wind - Solar flares can be accompanied by dense clouds of electrically charged particles, travelling at around 450km per second. When they reach Earth, they can affect communications satellites.


Unreachable, unimaginably hot and yet ever present. The sun is the source of all life on earth. It's little wonder many cultures still revere it as a deity. For 4.5 billion years the sun rises every morning on the horizon. But what do we really know about the heavenly ball of fire which provides us with light and warmth? This movie shows with impressive pictures the thrilling story of the creation of the sun, it's influence on our well-being, and how we could use it's power to change the future on earth dramatically.


The sun is the center of our universe and our calendar. The life-giver brightens our sky, provides us with light, warmth and nourishment. Yet the star itself is a very inhospitable place. At a surface temperature of 5.700 degree Celsius we have to be grateful that the sun is 150 million kilometers away from earth. But even at this distance it influences our lives more than we often care to imagine. Even in the age of electrical light the change from day to night remains obvious. But why are we so depressed when the sun doesn't reach us directly once in a while? Physicists have long since proved that depression is more likely to occur in winter than in summer. The culprit is very unlikely the cold of winter but rather the scarce natural light.


The activities of sunspots and cosmic weather often remain hidden to humans. Yet Galileo Galilei already documented the motion of the darker, colder spots on the surface of the sun. But their meaning was only discovered much later. In the middle of the 17th century the surface of the sun entered a phase where it remained completely free of sunspots. This in turn caused the last prolonged cold period in the northern hemisphere: the "miniature ice-age". Temperatures only fell by one to two degrees - but the distribution of polar pack ice obliterated entire viking settlements and caused the population of Iceland to go back by half. Why this was the case hasn't been revealed to the present day.


Though in the meantime another spectacle of the inconceivable solar forces is being observed: eruptions on the surface. Once the magnetic fields of of sunspots explode they fling billions of tons of plasma into space. These mighty gas-fountains often reach earth days later where the magnetic field of the earth blocks them to the greatest possible extent. Observable consequences of the impacts are polar lights, migratory birds which have lost their sense of orientation and stranded whales. Can humans use the unbelievable powers of the sun to avert a energy crisis and global warming?

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