| AURORA ALERTS:
Did you miss the Northern Lights of June 14th? Next time get
a wake-up call from Space
Weather PHONE. |
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NLC ALERT:
Summer is the season for noctilucent
clouds (NLCs) and yesterday's solstice kicked off an intense
display over the British Isles. Some veteran observers said the
clouds were as bright as they've ever seen. Readers, especially
you at high latitudes, be alert for NLCs in the evenings ahead;
observing tips may be found in the photo
gallery.
MARTIAN ICE:
Scientists have figured out the mysterious white substance unearthed
by NASA's Phoenix
lander on Mars. It's frozen water. The breakthrough came last week
when Phoenix's stereo camera caught the substance in the act of
disappearing:
Bathed in martian sunlight for four days, the white
substance sublimated--i.e., it transformed from solid to
gas without passing through the liquid state. This is how water
behaves on Mars. Atmospheric pressure on the Red Planet is so low
(1% that of Earth), it rarely allows H2O to exist in
liquid form on the planet's surface; solid and gas are the only
options. Some readers have asked, how do we know the white substance
is not frozen CO2 (dry ice) instead of frozen water?
Answer: Phoenix's landing site is too warm for dry ice. The average
daily temperature is about -70 F while dry ice requires temperatures
lower than about -109 F.
Finding water was one of the key goals of the Phoenix
mission. Although H2O has trouble flowing as a liquid
on the surface of Mars, it may be able to liquify, from time to
time, just below the surface, providing a habitat for martian microbes.
Exciting stuff! Stay tuned as the
digging continues.
ICE SEE 3D:
Ready to see martian ice vanish in three dimensions? Slip on your
3D
glasses and click
here. Belgian graphic artist Patrick
Vantuyne created the anaglyph by combining right- and left-eye
images from Phoenix's stereo camera.
SOLSTICE CELEBRATIONS:
No, this mountain in the Austrian Alps is not spewing lava. It's
a summer solstice celebration:
Zoom in and
zoom in again
to see what's really happening.
"This is a traditional solstice celebration in our part of
Europe," explains photographer Thorsten
Boeckel. "More than 8000 fires light up these 200-meter
figures in the steep mountain walls from an altitude of 1200m to
2900m. What an unique sight from a 2000m perch on the opposite side
of the valley."
more solstice photos: from
Andrew Greenwood at Jodrell Bank Observatory, Cheshire, England
May 2008 Aurora Gallery
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