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THE SUN'S SNEAKY VARIABILITY:
It might not be obvious to the naked eye,
but the sun is a variable star. A sensor slated for launch
onboard the Solar Dynamics Observatory will probe the sun's
"sneaky variability" with better time and spectral
resolution than ever before. Get the full
story from Science@NASA.
BIG SUNSPOT:
After five days of non-stop growth (movie),
sunspot 1029 has become the biggest active region of the year
and a beautiful target for backyard solar telescopes. Amateur
astronomer Lecoq Etienne sends this picture from Mesnil-Panneville,
France:
The sunspot's large dark core is about the size
of Earth, while the entire sunspot group stretches about 50,000
km from end to end. The behemoth has been crackling with magnetic
activity, producing 10 C-class
solar flares in the past few days. That more than triples
the number of C-flares (3) previously detected in all of 2009.
According to NOAA forecasters, there is a 5% chance of an
even stronger M-class
flare during the next 24 hours. Stay
tuned for solar activity!
more images: from
Dave Gradwell of Near Birr Ireland; from
Jimmy Eubanks of Boiling Springs, South Carolina; from
Gianluca Valentini of Rimini, Italy; from
Peter Paice of Belfast, Northern Ireland; from
John C McConnell of Maghaberry, Northern Ireland.
INDONESIAN ASTEROID:
Picture this: A 10-meter wide asteroid hits
Earth and explodes in the atmosphere with the energy of a
small atomic bomb. Frightened by thunderous sounds and shaking
walls, people rush out of their homes, thinking that an earthquake
is in progress. All they see is a twisting trail of debris
in the mid-day sky:
Click to view an Indonesian news report
This really happened on Oct. 8th around 11 am local time
in the coastal town of Bone, Indonesia. The Earth-shaking
blast received remarkably little coverage in Western press,
but meteor scientists have given it their full attention.
"The explosion triggered infrasound
sensors of the Comprehensive Nuclear-Test-Ban Treaty Organization
(CTBTO) more than 10,000 km away," report researchers
Elizabeth Silber and Peter Brown of the Univ. of Western Ontario
in an Oct.
19th press release. Their analysis of the infrasound data
revealed an explosion at coordinates 4.5S, 120E (close to
Bone) with a yield of about 50 kton of TNT. That's two to
three times more powerful than World War II-era atomic bombs.
The asteroid that caused the blast was not known before it
hit and took astronomers completely by surprise. According
to statistical studies of the near-Earth asteroid population,
such objects are expected to collide with Earth on average
every 2 to 12 years. "Follow-on observations from other
instruments or ground recovery efforts would be very valuable
in further refining this unique event," say Silber and
Brown.
October
Northern Lights Gallery
[previous Octobers: 2008,
2007, 2006,
2004, 2003,
2002, 2001]
Explore
the Sunspot Cycle |
