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SUBSIDING RADIATION
STORM: A solar radiation storm in
progress around Earth is slowly subsiding. It
currently ranks S2
(moderate) on NOAA storm scales, which means that
satellites in Earth orbit could experience "single
event upsets" in their electronic systems.
The radiation storm is also a source of noise in
spacecraft cameras, giving their images a snowy
appearance (see below).
M5-CLASS EXPLOSION:
The ongoing radiation storm got started on May 22nd
when the magnetic canopy of sunspot AR1745 exploded.
The blast produced an M5-class
solar flare and hurled a magnificent CME over the
sun's western limb:
Credit: the Solar and Heliospheric
Observatory (SOHO)
The movie
of the CME is very "snowy." That is
caused by high-energy solar protons striking the
CCD camera in SOHO's coronagraph.
Each strike produces a brief snow-like speckle in
the image. This hailstorm of solar protons is what
forecasters mean by "radiation storm."
Although the explosion was not squarely
Earth-directed, the CME will likely be geoeffective.
The expanding cloud appears set to deliver a glancing
blow to Earth's magnetic field on May 24th around
1200 UT. According to NOAA forecast models, the
impact will more than double the solar wind plasma
density around Earth and boost the solar wind speed
to ~600 km/s. High-latitude sky watchers should
be alert for auroras.
Aurora alerts:
text,
voice.
Realtime
Space Weather Photo Gallery
THE SHOW BEGINS:
The long-awaited sunset
sky show of May 2013 is beginning. In only a
few days, Venus, Jupiter and Mercury will form a
tight triangle in the western sky, visible to the
unaided eye around the world. On May 20th, Fred
Espenak of Portal, Arizona, photographed the trio
in the early stages of convergence:
"The three planets were easily
visible to the naked eye in spite of the bright
twilight glow," says Espanel. "Mercury
should be even easier to spot in the coming days
as it climbs higher into the sky. "
In the nights ahead, the line of planets
will collapse to form a triangle. At closest approach
on May 26th, they will fit within a circle less
than 3o wide. Start watching tonight--it's
a great way to end the day. [full
story] [video]
Realtime
Planet Photo Gallery
A BIG ASTEROID APPROACHES:
Near-Earth asteroid 1998
QE2 is approaching the Earth-Moon system for
a flyby on May 31st. There's no danger of a collision;
at closest approach the asteroid will be 3.6 million
miles away. Even at that distance, however, the
1.7-mile-wide space rock will be an easy target
for mid-sized backyard telescopes. Using a 14-inch
Celestron, Alberto Quijano Vodniza of Narino, Colombia
took this picture of 1998 QE2 on May 17th:
The sunlit side of the asteroid will
turn more squarely toward Earth during the first
week of June. At that time it will reach a maximum
brightness of 11th magnitude.
NASA radars will be monitoring the
flyby, too. "Asteroid 1998 QE2 will be an outstanding
radar imaging target at Goldstone and Arecibo and
we expect to obtain a series of high-resolution
images that could reveal a wealth of surface features,"
says
radar astronomer Lance Benner of JPL. "Whenever
an asteroid approaches this closely, it provides
an important scientific opportunity to study it
in detail to understand its size, shape, rotation,
surface features, and what they can tell us about
its origin."
Stay tuned for updates and observing
tips.
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