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DEEP SOLAR MINIMUM:
Where have all the sunspots gone? As of yesterday, March 21st, the
sun has been blank on 85% of the days of 2009. If this rate of spotlessness
continues through the end of the year, 2009 will match 1913 as the
blankest year of the past century. A flurry of new-cycle sunspots
in Oct. 2008 prompted some observers to declare that solar minimum
was ending, but since then the calm has returned. We are still in
the pits of a deep solar minimum.
SPACE STATION FLARES:
Everyone knows the ISS is bright. But this
bright? Last night when the station flew over the Netherlands, its
luminosity surged to super-Venus levels. "I estimated it to
be at least visual magnitude -5," reports Marco Langbroek of
Leiden. "Leo Barhorst observing 35 km northeast of me estimated
at least -6." These numbers mean the ISS was four times brighter
than Venus and 40 times brighter than Sirius, the brightest star
in the sky.
Dutch astronomer Quintus Oostendorp observed the flare through
his backyard telescope. This snapshot shows what happened:
No, it is not an explosion. The bright flash is sunlight glinting
off the station's enormous solar arrays. On March 20th, astronauts
unfurled a new pair of arrays on the space station's starboard side,
adding 8000 sq. feet of light-catching surface area to the station's
profile. The extra area increases both the chances and the luminosity
of ISS flares. "It was a spectacular sight!" says Oostendorp.
When will the ISS flare over your backyard? Check the Simple
Satellite Tracker for flybys.
more images: from
Pawel Warchal of Cracow, Poland; from
Ralf Vandebergh
of the Netherlands; from
Janusz Krysiak of Koluszki, Poland; from
Martin Wagner of Sonnenbuehl, Germany; from
Rob Carew of Melbourne Australia;
more movies: from
Dirk Ewers of Germany (DivX required);
from
Dave Gallant of Thunder Bay, Ontario, Canada; from
Mike Tyrrell of Northwich, Cheshire, UK;
NEAR THE EDGE OF THE
SUN: Imagine looking up at noon and seeing
a planet with four moons just 0.1o from the edge of the
blinding sun. Impossible? NASA's STEREO-B spacecraft did it this
week. Click on the image below to launch a movie of Jupiter and
the Galilean satellites in close "solar conjunction."
5
MB Quicktime movie | labeled
still frame | Zoom
in on Jupiter
During the 30-hour movie, Io, Europa, Ganymede and
Callisto circle Jupiter as a massive CME billows overhead. STEREO-B
recorded the action on March 15th and 16th using an occulting disk
to block the solar glare. This arrangment allowed STEREO's cameras
to photograph moons of Jupiter eight thousand billion (8x1012)
times dimmer than the adjacent sun.
STEREO's coronagraph (occulting disk+camera) is designed
to monitor faint but powerful activity in the sun's outer atmosphere.
The CME is a good example. With a limiting magnitude of +6.5, it
can also see stars, planets, moons and comets so close to the edge
of the sun, it seems impossible. In fact, it happens all the time.
Browse the STEREO
gallery for examples.
March
2009 Aurora Gallery
[previous Marches: 2008,
2007, 2006,
2005, 2004,
2003, 2002]
Comet
Lulin Photo Gallery
[Comet
Hunter Telescope: review]
[Comet
Lulin finder chart]
Explore
the Sunspot Cycle
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