SATELLITE
FLYBYS APP: Turn your iPhone or iPod into
a field-tested satellite tracker! Spaceweather.com presents
the Satellite Flybys
app. |
|
|
AURORA ALERT:
High-latitude sky watchers should be
alert for auroras.
Earth is entering a dense solar wind stream and this could
trigger polar geomagnetic storms.
CRACKLING SUNSPOT:
Old sunspot 1039 is crackling with solar flares. Over the
past 48 hours, it has produced five M-class
eruptions. Click on the image to play a movie of the latest,
an M2-blast recorded by STEREO-B at 1756 GMT on Jan. 20th:
The ongoing sequence
of flares signals a sharp upturn in solar activity. Before
this week, the last time the sun produced even a single M-class
solar flare was in March 2008--almost two years ago. M-class
solar flares have a moderate effect on Earth. Mainly, they
boost the usual ionization of Earth's upper atmosphere, causing
short-lived radio blackouts at some frequencies and radio
enhancements at others. For an example, scroll down and read
the section "Ionospheric Disturbance."
Today, the active region responsible for these fireworks
is emerging over the sun's eastern limb where it can be seen
from Earth: finder
chart. Readers with solar
telescopes are encouraged to monitor developments.
IONOSPHERIC DISTURBANCE:
An M2-class solar flare on Jan. 19th bathed Earth's upper
atmosphere in X-rays and caused a wave of ionization to sweep
over Europe. This improved the propagation of low-frequency
radio signals, which use the
ionosphere as a reflector to skip over the horizon. A
SID monitor operated by Rudolf Slosiar in Bojnice, Slovakia,
recorded a surge in signal strength:
"SID" stands for Sudden Ionospheric Disturbance,
and a "SID monitor" is a radio receiver that monitors
~20 kHz signals from distant transmitters. "My system
clearly detected the effects of the solar flare," says
Slosiar. "The decay of the signal shows that it took
about 72 minutes for the ionosphere to recombine [and relax
to its pre-flare state]."
With solar activity on the rise, sudden ionospheric disturbances
will become more common. Interested? Stanford University tells
you how to build your
own SID monitor.
more SIDS: from
Roberto Battaiola of Pantigliate, Milano, Italy;
January
Northern Lights Gallery
[previous Januarys: 2009,
2008, 2007,
2005, 2004,
2001]
UPDATED: Solar
Eclipse Photo Gallery
[World
Map of Eclipse Sightings]
|
