- On the night of 27 August the Earth's
upper atmosphere was bathed briefly by an invisible burst of high energy
radiation from deep space.
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- The pulse of energy, the most powerful
detected to strike the Earth from beyond the solar system, had a significant
effect on the planet's upper atmosphere, scientists say.
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- It is the first time that a significant
change in the Earth's atmosphere has been traced to a distant star.
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- Professor of Electrical Engineering at
Stanford University in California, Umran Inan, said: "It was as if
night was briefly turned to day in the ionosphere."
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- The energy pulse came from a distant
star designated SGR 1900+14. It lasted just five minutes but scientists
estimate that the pulse contained enough energy to power all of human civilisation
for a billion billion years.
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- The object 1900+14 is believed to be
a superdense star called a neutron star whose gravity pulls material from
a nearby star.
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- This material comes crashing down onto
the neutron star becoming superhot and finally exploding sending out a
titanic burst of energy.
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- Five-minute disturbance
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- Scientists at Stanford operate a string
of radio receivers across North America designed to monitor the state of
the ionosphere, the region between 60 and 80 kilometres high. It detected
a severe, five-minute disturbance on 27 August.
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- During that time the ionosphere pulsed
to a five-second rhythm. This is the orbital period for the 1900+14 neutron
star to rotate.
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- The burst was also picked up by the deep
space Ulysses spaceprobe that is orbiting the Sun 600 million miles away.
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- This is not the first time that a stellar
burst from outside the solar system is believed to have affected the Earth.
Other events may have been observed in 1983 and 1996.
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- It is however the first time that there
is definite evidence for such an effect.
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- Although there was no danger to life
on Earth, the pulse was far too weak for that, scientists do believe that
if a star exploded in our local cosmic neighbourhood its radiation could
affect our atmosphere and sterilise the Earth's surface.
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