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magazine / ma05
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March/April 2005 issue |
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Auroral inquest
Setting the boundaries for Alberta and Saskatchewan was no easy feat.
There were many competing ideas on how to carve up the prairies
By Jodi Di Menna and Steven Fick
If you’ve ever stood outside, eyes heavenward, as the bright green arc
of the aurora borealis breaks into a red, purple and white jitterbug, then
you’ve been witness to one of the most perplexing problems of magnetospheric
physics. This sequence of events is known as an auroral substorm, and finding
out exactly what causes it is the objective of a groundbreaking photo-imaging
project led by scientists at the University of Calgary and the University of
California, Berkeley.
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| Photo: NASA |
A few times each year, the sun blasts out millions of tonnes of charged particles,
and massive solar flares — like the one (right) that occurred in October 2003 — explode
from its surface, triggering magnetic storms that can knock out satellites and
disrupt power grids. But they also produce spectacular auroral displays farther
south than normal as a flurry of protons and electrons from the sun are swept
toward the poles of the Earth’s magnetic field and rain into the upper
atmosphere. There, they collide with atoms, releasing bursts of light that dance
across the sky when the substorms kick in. Seen from a satellite, a northern
aurora appears as a bright oval ring shifting around the north magnetic pole
(below).
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| Photo: NASA |
By October 2006, an array of 20 ground-based digital cameras will snap photos of
the shifting aurora borealis every five seconds. Scientists are trying to explain
how a substorm starts.
Although their motivation is, for the most part, raw scientific curiosity, says
Canadian team leader Eric Donovan, any new knowledge that helps illuminate the
sun’s impact on the Earth could have important economic implications.
"We’re increasingly doing business in space," says Donovan,
who is funded by the Canadian Space Agency. "From weather satellites to
telecommunications, we each use space in one way or another every day. This project
will help us understand this region in leaps and bounds."
Movie of a solar flare from
2003.
Movie of the sky viewed
on one night in November 2004, from one of the first sites of the THEMIS project
(Athabasca). Also, 42 individual
thumbnail shots of the sky from that same night.
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