I thought all you Elecrafters out there would find this interesting:
Mystery of northern lights revealed
SATELLITES: Magnetic explosions in space trigger the dancing displays.
By MARCIA DUNN
The Associated Press
CAPE CANAVERAL, Fla. -- Scientists have exposed some of the mystery
behind the northern lights.
On Thursday, NASA released findings that indicate magnetic explosions
about one-third of the way to the moon cause the northern lights, or
aurora Borealis, to burst in spectacular shapes and colors, and dance
across the sky.
The findings should help scientists better understand the more powerful
but less common geomagnetic storms that can knock out satellites, harm
astronauts in orbit and disrupt power and communications on Earth,
scientists said.
A fleet of five small satellites, called Themis, observed the beginning
of a geomagnetic storm in February, while ground observatories in Canada
and Alaska recorded the brightening of the northern lights. The southern
lights -- aurora Australis -- also brightened and darted across the sky
at the same time.
These auroral flare-ups occur every two or three days, on average.
A team led by University of California, Los Angeles, scientist Vassilis
Angelopoulos confirmed that the observed storm about 80,000 miles from
Earth was triggered by a phenomenon known as magnetic reconnection.
Every so often, the Earth's magnetic field lines are stretched like
rubber bands by solar energy, snap, are thrown back to Earth and
reconnect, in effect creating a short circuit.
It's this stored-up energy that powers the northern and southern lights
or, in other words, causes them to dance, according to Angelopoulos.
An opposing theory has these geomagnetic events occurring much closer to
Earth, about one-sixth of the way to the moon. More Themis observations
are needed to resolve the debate, said David Sibeck, NASA's project
scientist.
"Finally, we have the right instruments in the right place at the right
time, and it's allowed scientists to be able to make the necessary
observations to settle this heated debate once and for all," said Nicola
Fox, a Johns Hopkins University scientist who was not involved in the study.
At present, about 20 of these geomagnetic storms are being analyzed.
Scientists hope to eventually learn, via this project, more about the
bigger solar storms that occur about 10 times a year and can lead to far
more expansive and prolonged northern and southern lights.
The five Themis spacecraft -- a NASA acronym standing for Time History
of Events and Macroscale Interactions during Substorms -- were launched
aboard a single rocket last year.
_______________________________________________
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com