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NEW SOLAR CYCLE PREDICTION:
An international panel of experts has issued
a new prediction for the solar cycle which takes into account the
surprisingly deep solar minimum of 2008-2009. Read today's
story from Science@NASA to find out when they think solar maximum
will return.
FIRST NLCs of 2009:
New data from NASA's AIM spacecraft show
that noctilucent
clouds (NLCs) are like a great "geophysical light bulb."
They turn
on every year in late spring, reaching almost full intensity
over a period of no more than 5 to 10 days.
News flash: The bulb is beginning to glow. The first NLCs of 2009
were sighted over Russia on May 27th, and an even brighter display
appeared last night, May 29th, over Denmark and the British Isles.
Martin Mc Kenna sends these snapshots from Maghera, Northern Ireland:
"The glowing clouds were more than 100 degrees wide with white,
blue and even subtle yellow and green colours," says Mc Kenna.
"It was an excellent display to start the season and a good
omen of major events to come in the near future!"
The display was also witnessed by from John C Mcconnell of Maghaberry
Northern Ireland (photos);
Paul Evans of Larne, Northern Ireland (photos);
and Ian Brantingham near Banff, Scotland (photos).
There is a well-known correlation
between noctilucent clouds and the solar cycle. NLC activity tends
to peak during years of solar minimum, possibly because low solar
activity allows the upper atmosphere to cool, promoting the growth
of ice crystals that make up the clouds. With a century-class
solar minimum underway, the stage is set for a good season of
NLC watching.
Typically, the first NLCs of spring are wan and pale, followed
by better displays as summer unfolds. Browse the galleries from
previous years to see what may be in the offing: 2008,
2007, 2006,
2005, 2004,
2003.
JUPITER'S MOON SHOW:
Every six years, Earth spends a number of
months passing through the orbital plane of Jupiter's moons. During
the passage, amateur astronomers get to see a rare display of "mutual
occultations." Jupiter's moons eclipse one another in plain
view of backyard telescopes.
On May 25th, Mike Salway of Central Coast, Australia, watched Ganymede
eclipse Io. Click on the still-frame to launch a 0.25 MB movie:
Images like these are unprecedented. Although Jupiter's moons put
on the same kind of show in 2002-2003, no one recorded such clear
pictures. "Imaging techniques and equipment have improved immensely
over the past 6 years," notes Salway. "So this is the
first year where amateurs are recording these events and producing
detailed, high-resolution images of the phenomena."
If you missed the Ganymede-Io eclipse, don't worry. There are plenty
more to come. Mutual occultations of Jupiter's moons will continue
from now until nearly the end of the year. As part of the International
Year of Astronomy, professional astronomers are organizing a worldwide
observing campaign to record as many of these events as possible.
Click here
for details.
more images: from
Efrain Morales Rivera of Aguadilla, Puerto Rico; from
Paul Maxson of Surprise, Arizona
April
2009 Aurora Gallery
[previous Aprils: 2008,
2007, 2006,
2005, 2004,
2003, 2002]
Explore
the Sunspot Cycle
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