iPHONE VS
ANDROID! Actually, it doesn't matter which
phone you carry. Our cool, new app turns both smartphones
into field-tested satellite trackers. Learn
more. |
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COMET
HARTLEY AND THE OWL: The comet
show continues. After visiting the
Pacman nebula on Oct 1st and 2nd, green Comet
103P/Hartley 2 is now paying a call on the
Owl cluster. Readers with wide-field telescopes
are encouraged to monitor the comet's busy track
across Cassiopeia in the nights ahead--especially
Oct. 7th and 8th when the comet glides a mere 1o
from the photogenic Double Cluster. Details
and a sky
map are available from from Sky & Telescope.
LOST
AND FOUND: XSS-11 SPYSAT: On Sept.
20, 2010, amateur satellite watcher Kevin Fetter
was monitoring the traffic over his home in Brockville,
Canada, when a bright flash attracted his attention.
"It can be seen at the beginning of this
video," says Fetter. "At first I had
no idea what it was." A rough orbit calculated
by Fetter with refinements added by sat-tracking
expert Ted Molczan suggested an intriguing possibility:
Could it be long-lost military
satellite XSS-11? Indeed it was. Follow-up sightings
by Alberto Rango (Sept. 29) and Russell Eberst (Sept.
30) confirmed the recovery, and on Oct. 3rd Fetter
video recorded the XSS-11 again. Click on the image
to set the satellite in motion:
The washing-machine-sized spacecraft was launched
by the US Air Force in April 2005 to demonstrate
"autonomous rendezvous and proximity maneuvers."
In other words, it would approach, investigate,
and photograph other spacecraft in Earth orbit.
The mission was controversial
because it aimed to prove technologies that could
potentially be used for anti-satellite weapons.
For some 18 months in 2005 and 2006, amateur satellite
watchers kept track of the XSS-11 as it visited
at least two other orbiting objects: the body of
the Minotaur rocket that launched it and a military
DMSP weather satellite. "XSS-11 soon completed
its mission, and in December 2006, it was manoeuvred
into a disposal orbit, i.e. one with a
sufficiently low perigee to reduce the time to decay
from centuries to decades," recalls Molczan.
"The dimensions and inclination of the new
orbit were made public, but without complete orbital
elements, it would have been difficult to find.
I expected that eventually, it would be spotted
as an unknown object, which is what happened on
2010 Sep 20 UTC, when Kevin Fetter noticed something
make a brief, bright flash on his monitor."
"Except for the ISS toolbag, this is the smallest
satellite I have ever recorded," says Fetter.
"I might not have found it except for that
flash. At maximum, it was about 4th magnitude, visible
to the naked eye in a good dark sky." Presumably,
some flat surface on the XSS-11 is glinting in sunlight,
attracting a degree of attention that belies the
satellite's modest dimensions.
See for yourself. A schedule of XSS-11 flybys is
available on your
cell phone and on the web.
STEAM
DEVIL SEASON: Alert. Steam devil
season is underway. In early autumn when waters
are still warm but morning air is growing cold,
little tornadoes of steam are often seen dancing
across lake surfaces. Andrew Pritchard caught this
one on Deep Lake, Wisconsin, at sunrise on Oct.
2nd:
"I was at my lake house in central Wisconsin
during the area's first hard freeze," says
Pritchard. "The air temperature plunged below
30F. With water temperatures in the lake still above
60F, I figured photogenic morning steam would be
a sure thing. The steam devils started sprouting
up around sunrise. Light winds blowing across the
lake surface created little areas of vorticity,
which were stretched by updrafts into tall and tight
circulation patterns. Pretty mesmerizing stuff to
watch as they really do resemble little water spouts."
Pritchard's video
of his experience will make you want to find a lake
and wake up at dawn.
Sept.
2010 Northern Lights Gallery
[previous Septembers: 2009,
2008,
2007,
2006,
2005,
2004,
2002,
2001,
2000]
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
October 5, 2010 there were 1147
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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from
the National Solar Data Analysis Center |
