RADAR
IMAGES OF COMET HARTLEY 2: What
is the shape of nearby Comet Hartley 2? On October
24th, astronomers used the giant Arecibo radar to
image the comet's core. And the answer is ... "a
cross between a bowling pin and a pickle,"
reports Tim Larson of NASA's Jet Propulsion Laboratory.
According to the
radar images, the "pickle" is 2.2
km long and spins around it's short axis once every
18 hours. The Deep Impact (EPOXI) probe will get
a
closer look on Nov. 4th when it flies by the
comet at a distance of only 435 miles. Stay tuned.
COMET UPDATE:
Amateur astronomers report that they can once again
see Comet Hartley 2 through backyard
telescopes as the morning moon fades in brightness.
latest images: #1,
#2,
#3.
AMAZING
HALOES: On Oct. 30th in Kittilä,
Finland, photographer Sauli Koski witnessed a brief
but unforgettable display when the rising sun shone
through a morning cloud of wintery ice crystals.
Fortunately he had his camera:
Full sized images:
labeled
or unlabeled
"These were the best ice
haloes I have ever seen," says Koski. "They
were there for only about 10 minutes and then gone.
What a delight!"
"It was a gem of a halo display,"
agrees atmospheric optics expert Les Cowley. "Koski
saw at least 13 different arcs. Some, including
two types of Parry arc, are rare. Three more arcs,
the helic,
Parry
supralateral, and Moilanen
are exceedingly rare. See
the key for the arc identities. With winter
fast approaching, now is the time for outstanding
halos."
more images: from
Oleg Toumilovitch of Johannesburg, South Africa;
from
Inge Malan of Woodmead, Johannesburg, South
Africa; from
Dawn Wyngaard of Johannesburg, South Africa;
from
Tinyiko Chauke of Pretoria, Gauteng ,South Africa
DANGEROUS
BEAUTY: As November begins, Venus
is passing almost directly between Earth and the
sun, an event astronomers call "inferior conjunction."
The view through a telescope is both beautiful and
dangerous. Henry Mendt of Maracaibo, Venezuela,
took this daylight picture of Venus only 7o
from the blinding sun on Oct. 31st:
Venus is such a slender crescent because
the planet's night side is almost-squarely facing
Earth. "Only 0.7% of the disk was illuminated,"
says Mendt, "but the crescent was bright and
wide, a full arcminute in diameter. This made Venus
easy to find even in the midday sky." Here
he describes how he safely targeted Venus using
an 8-inch telescope
and photographed the planet from inside the shadows
of a parking garage.
Venus will become even easier to find
in the weeks ahead as it emerges from the glare
of the sun into the pre-dawn sky. The crescent will
be a little fatter, but much less dangerous and
no less beautiful. Stay tuned for the
Morning
Star.
more images: from
Somsawat Rattanasoon of Chiang Mai, Thailand;
from
Jim Werle of Henderson, Nevada
October
2010 Aurora Gallery
[previous Octobers: 2009,
2008,
2007,
2006,
2004, 2003,
2002,
2001]
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
November 1, 2010 there were 1157 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.
| |
The
official U.S. government space weather bureau |
| |
The
first place to look for information about sundogs,
pillars, rainbows and related phenomena. |
| |
Researchers
call it a "Hubble for the sun." SDO is the most
advanced solar observatory ever. |
| |
3D
views of the sun from NASA's Solar and Terrestrial
Relations Observatory |
| |
Realtime
and archival images of the Sun from SOHO. |
| |
from
the NOAA Space Environment Center |
| |
the
underlying science of space weather |
