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COMET
ENCOUNTER-TONIGHT! NASA's Stardust-NExT
probe is plunging toward Comet Tempel 1 for a Valentine's
Day encounter designed to reveal how solar
heat devours the icy cores of comets. Closest
approach happens at 8:37 p.m. PST (11:37 p.m. EST)
on Feb. 14th. Stay tuned for fantastic images.
EARTH-DIRECTED
SOLAR FLARE: On Feb. 13th at 1738
UT, sunspot 1158 unleashed the strongest solar flare
of the year so far, an M6.6-category
blast. NASA's Solar Dynamics Observatory recorded
an intense flash of extreme ultraviolet radiation,
circled below:
The eruption produced a loud blast of radio waves
heard in shortwave receivers around the dayside
of our planet. In New Mexico, amateur radio astronomer
Thomas Ashcraft recorded these
sounds at 19 to 21 MHz. "This was some
of the strongest radio bursting of the new solar
cycle," he says. "What a great solar day."
Preliminary coronagraph data from STEREO-B and
SOHO agree that the explosion produced a fast but
not particularly bright coronal mass ejection (CME).
The cloud will likely hit Earth's magnetic field
on or about Feb. 15th. High-latitude sky watchers
should be
alert for auroras.
The source of this activity, sunspot 1158 is growing
rapidly. Click on the image to launch a 2-day movie:
Barely visible when the weekend began, the active
region is now more than 100,000 km wide with more
than half-a-dozen Earth-sized dark cores scattered
beneath its unstable magnetic canopy. More Earth-directed
eruptions are likely in the hours ahead.
more images: from
Luca Tesoro of Mercogliano (AV), Italy; from
Michael Buxton of Ocean Beach, California; from
Strikis Iakovos - Marios of Athens Greece (Haidari);
February
2011 Aurora Photo Gallery
[previous Februaries: 2010,
2009,
2008,
2007, 2006,
2004, 2003,
2002]
Potentially 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 finding new
ones all the time.
On
February 14, 2011 there were 1198
potentially hazardous asteroids.
Notes: LD means
"Lunar Distance." 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.
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The
official U.S. government space weather bureau |
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The
first place to look for information about sundogs,
pillars, rainbows and related phenomena. |
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Researchers
call it a "Hubble for the sun." SDO
is the most advanced solar observatory ever. |
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3D
views of the sun from NASA's Solar and Terrestrial
Relations Observatory |
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Realtime
and archival images of the Sun from SOHO. |
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from
the NOAA Space Environment Center |
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the
underlying science of space weather |
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