AURORA ALERTS: Did you miss the Northern Lights? Next time
get a wake-up call from Space
RADIO ECHOES: During the geomagnetic
storm of Nov. 27th, a brief but intense
G2-class event, amateur radio operator Peter
Brogl of Fürth, Germany, experienced a strange
phenomenon. Forty-six seconds after he transmitted
his call sign at 7 MHz, he received an echo of his
own transmission. "At first, I thought someone
was playing tricks on me," says Brogl, "but
I changed frequency, re-keyed my call sign (DK6NP),
and got another echo." This went on for more
than an hour, enough time for Brogl to make several
recordings. First reported in 1927 by Norwegian
civil engineer Jørgen Hals, long-delay
radio echoes are rare and poorly understood.
Unusual propagation conditions linked to solar storms
is one of many possible
explanations. Radio operators, if you experienced
any similar phenomena on Nov. 27th between 1800
UT and 19:30 UT, please report
your observations to Peter Brogl for correlation.
CANOPY: Two days ago, sunspot 1130
didn't exist. Now the fast-growing sunspot group
is the largest visible feature on the sun's disk
with twin cores both larger than Earth. The amazing
thing, however, is the invisible part.
Using extreme ultraviolet filters outside the range
of human vision, NASA's Solar Dynamics Observatory
took this picture of the sunspot's magnetic canopy
on Nov. 30th:
In the image, curvaceous lines of
magnetism are illuminated by hot solar plasma trapped
inside the canopy. If the magnetic field becomes
unstable and explodes, as sunspot magnetic fields
often do, a cloud of plasma could come flying toward
Earth. This active region merits watching for the
next few days until the sun's rotation turns it
away from our planet. Stay
OF JUPITER'S MISSING STRIPE: The
revival of Jupiter's South Equatorial Belt (SEB),
for nearly a year, is now well underway. The
roiling, turbulent disturbance that heralds the
brown stripe's full return stretches almost halfway
around the giant planet. "Here is a projection
map showing the revival on Nov. 29th," says
amateur astronomer Wayne Jaeschke of West Chester,
Pennsylvania. Note the region bracketed by arrows:
"I made the map by combining
two pictures of Jupiter I took using my 14-inch
Celestron telescope," says Jaeschke. "The
disturbance has grown dramatically since it first
appeared in late October." Indeed, it is now
so large that even novice observers are starting
to notice it in the eyepieces of backyard telescopes.
The spreading disturbance is not the
SEB itself. Instead, it is thought to be a progressive
clearing of high clouds that will eventually reveal
the brown stripe hiding below. When the SEB finally
returns, Jupiter will have two brown stripes again
and the planet's appearance will return to normal.
Meanwhile, amateur astronomers are encouraged to
monitor the revival. Point your optics south after
more images: from
Wayne Jaeschke of West Chester, PA; from
Geoff Chester of Alexandria, Virginia; from
John Nassr of Baguio, Philippines
2010 Aurora Gallery
[previous Novembers: 2009,
Hazardous Asteroids (PHAs
are space rocks larger than approximately 100m that can come
closer to Earth than 0.05 AU. None of the known PHAs is on
a collision course with our planet, although astronomers are
all the time.
November 30, 2010 there were 1164
potentially hazardous asteroids.
Notes: LD means "Lunar
1 LD = 384,401 km, the distance between Earth and the Moon.
1 LD also equals 0.00256 AU. MAG is the visual magnitude
of the asteroid on the date of closest approach.
official U.S. government space weather bureau
first place to look for information about sundogs,
pillars, rainbows and related phenomena.
call it a "Hubble for the sun." SDO is the most
advanced solar observatory ever.
views of the sun from NASA's Solar and Terrestrial
and archival images of the Sun from SOHO.
the NOAA Space Environment Center
underlying science of space weather