The past month has been an amazing one for the Northern Lights, colorful sky shows called auroras that are fueled by solar storms
The past month has been an amazing one for the Northern Lights, colorful sky shows called auroras that are fueled by solar storms. Last night, rather unexpectedly, an ejection of charged solar particles generated aurora as far south as Florida. Residents of Georgia, Maryland and Virginia reported seeing the elusive curtains of color.
Few residents at such southern latitudes are so lucky. The auroras can come and go in a matter of minutes. But folks who live in the northern tier of the United States and Europe get more opportunities.
This picture was taken by Chris VenHaus earlier this year from Wisconsin. That's VenHaus on the dock. He used a self-timer to get the shot. VenHaus has more aurora photographs at his web site, including some available as prints.
Pictures of yesterday's auroras are included in
our story
about the storm. Also see our gallery
of aurora images.
The Northern Lights are created when a solar storm
interacts with Earth's magnetic field. The
field lines emanate from the planet's poles and extend well beyond the atmosphere.
In the interaction, local particles are accelerated
and race down the magnetic field lines, toward the poles. When they collide
with gas in the atmosphere, they excite the atoms and molecules to give off
light.
High-altitude oxygen, about
200 miles up, is the source of rare, all-red auroras, according to Hal Kibbey
of Indiana University. Oxygen at lower altitudes, about 60 miles up, produces
a brilliant yellow-green, the brightest and most common auroral color. Ionized
nitrogen molecules produce blue light, and neutral nitrogen glows red. The nitrogens
create the purplish-red lower borders and rippled edges seen
in some of the most dazzling aurora.
-- Robert
Roy Britt
Credit: Chris VenHaus
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