From: LARRY KLAES (ljk4_at_msn.com)
Date: Fri Aug 27 2004 - 19:08:34 PDT
----- Original Message -----
From: bulletins_at_SkyandTelescope.com<mailto:bulletins_at_SkyandTelescope.com>
To: ljk4_at_msn.com<mailto:ljk4_at_msn.com>
Sent: Friday, August 27, 2004 8:18 PM
Subject: S&T's Weekly News Bulletin for August 27
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* * * SKY & TELESCOPE's WEEKLY NEWS BULLETIN - August 27, 2004 * * *
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Welcome to S&T's Weekly News Bulletin. Images, the full text of stories
abridged here, and other enhancements are available on our Web site,
SkyandTelescope.com, at the URLs provided below. (If the links don't work,
just manually type the URLs into your Web browser.) Clear skies!
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TINY TELESCOPE FINDS BIG PLANET
Until now, all of the 125 or so known extrasolar planets were discovered
with large telescopes equipped with cutting-edge detectors. But an
international team has identified a planet circling a distant star using
mostly off-the-shelf equipment and a 4-inch Schmidt telescope. In fact,
team coleader Timothy Brown (National Center for Atmospheric Research)
assembled the discovery telescope and fine-tuned its optics in the garage
of his Colorado home....
> http://SkyandTelescope.com/news/article_1330_1.asp
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SEDNA'S ORIGIN SOLVED?
Last year astronomers discovered what's probably the biggest body found in
the solar system since Pluto in 1930, and they didn't know what to make of
it. Sedna, as 2003 VB12 was informally named, is about half the size of
the Moon and ranges from 75 to 985 astronomical units from the Sun in a
highly elliptical orbit. Neptune, by comparison, is 30 a.u. from the Sun,
Pluto averages 40 a.u., and the icy objects populating the Kuiper Belt
drop off sharply after 55.
So how did Sedna get way out there? It couldn't have formed in place; the
Sun's protoplanetary disk was too sparse that far out. Now Alessandro
Morbidelli (Cote d'Azur Observatory) and Harold F. Levison (Southwest
Research Institute) have analyzed various theories in detail....
> http://SkyandTelescope.com/news/article_1326_1.asp
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PERSEIDS PEAK AS PREDICTED
This is an exciting time to be a meteor observer. Scientists have long
known that a meteor shower occurs when the Earth passes through the trail
of debris strewn behind a comet as it orbits the Sun, but until a few
years ago they could only guess what would happen during any given shower.
Skilled observers would note unexpected outbursts and lulls, but nobody
knew how to use that data. Now, experts in orbital dynamics have started
to analyze the fine structure of these cometary debris trails and predict
fluctuations in meteor activity with extraordinary accuracy....
Now meteor prediction has scored another success. Esko Lyytinen of Finland
and Tom Van Flandern of Washington, DC, forecast an unusually brief and
intense peak in the 2004 Perseids due to a filament of debris cast off
when Comet Swift-Tuttle swept by the Sun in 1862. They also predicted that
the normal peak of this shower would be stronger than usual due to a
12-year resonance with Jupiter's orbit.
Preliminary analysis of data from 107 observers in 27 countries by Rainer
Arlt of the International Meteor Organization confirm both of those
predictions....
> http://SkyandTelescope.com/observing/objects/meteors/article_1329_1.asp
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ASTRO NEWS BRIEFS
Astronomers Find Lightweight Exoplanet
The European planet-hunting team led by Michel Mayor (Geneva Observatory,
Switzerland) has announced a low-mass planet orbiting the 5th-magnitude
southern star Mu Arae. The planet has a minimum mass of just 14 Earths,
almost identical to the mass of Uranus. It races around the solar-type
star every 9.5 days at an average distance of just 0.09 astronomical unit.
Because we do not know the inclination of the planet's orbit, its most
likely mass is actually about 17 or 18 Earths, similar to Neptune. This
object is the lightest planet discovered outside the solar system other
than the three terrestrial-mass bodies orbiting the pulsar B1257+12. Mu
Arae also has a previously discovered, Jupiter-mass planet in a 650-day
orbit, and there are strong indications of another planet even farther
out.
Like the vast majority of the 140 or so known extrasolar planets,
astronomers discovered this new object by tracking back-and-forth Doppler
shifts in the star's spectrum induced by the planet's gravitational pull.
The detection method does not reveal whether the planet is a large ball of
rock and iron (a so-called "super-Earth"), a gas giant like Jupiter and
Saturn, or a hybrid Uranus- or Neptune-like world with a massive rock/ice
core and a moderate gaseous envelope. Mayor's group discovered the planet
with its new super-high-resolution HARPS spectrograph on the 3.6-meter
European Southern Observatory telescope at La Silla, Chile.
Space Rock Buzzes Earth
Last March 31st, a small chunk of asteroid hurtled within 6,500 kilometers
of Earth's surface, according to an orbital analysis announced this week.
Now designated 2004 FU162, the object was spotted only hours before its
close brush by the LINEAR survey telescope in New Mexico. Unfortunately,
LINEAR recorded the speeding visitor on only four frames over a 44-minute
period. By the time astronomers were alerted to its existence, the little
asteroid had moved into the daylight sky. Despite these all-too-brief
observations, dynamist Steven Chesley (Jet Propulsion Laboratory) managed
to derive a reliable orbit -- and the near miss -- that was reported
August 22nd by the Minor Planet Center in Cambridge, Massachusetts.
With an estimated diameter of less than 10 meters, 2004 FU162 is small
enough that it would have exploded harmlessly had it collided with Earth's
atmosphere. Alan Harris (Space Science Institute) notes that an asteroidal
fragment of this size should pass just as close to Earth at least once per
year. "This event is not particularly rare," comments impact specialist
David Morrison (NASA-Ames Research Center), "except that LINEAR had the
good fortune to notice it."
The closest known near-miss asteroid skimmed within 60 km of Earth on
August 10, 1972, creating a dazzling daylight fireball seen along a
1,500-km-long trajectory over the Rocky Mountains. Its estimated diameter
was also about 10 meters.
Mars Odyssey Starts Extended Mission
After 23 months of scrutinizing the red planet's surface and atmosphere
from orbit, NASA's Mars Odyssey orbiter has officially completed its
primary mission. The spacecraft was launched on April 7, 2001, and reached
Mars 6 months later on October 23rd. A full Martian year has passed since
February 2002, when the orbiter began its scientific studies. In that time
the spacecraft confirmed that Mars has vast reserves of water ice just
below its surface, especially in and around the south pole, and its
infrared spectrometer has compiled a global map of mineral abundances and
surface textures. From this point forward Odyssey will carry out an
extended scientific mission, as it continues to relay 85 percent of the
images and other data transmitted by the twin rovers Spirit and
Opportunity.
New Nebula's X-rays
Backyard observer Jay McNeil's discovery of a nebula in January generated
much excitement among amateur astronomers and considerable interest on the
part of professionals. The previously invisible nebula suddenly lit up
when the star embedded within it brightened, probably because of a sharp
increase in the amount of matter falling onto it from its circumstellar
disk. Just a few weeks after McNeil spotted the object in one of his CCD
images, Joel H. Kastner (Rochester Institute of Technology) and his
collaborators realized that, by chance, they had imaged the region with
the Chandra X-ray Observatory in 2002, before the outburst began. They
have observed it twice since then, recording a 50-fold increase in the
object's X-ray luminosity that mirrors the brightening in optical and
infrared wavelengths. X-ray emission is commonly seen in young stars, but
there is an ongoing debate about what causes it. The fact that this X-ray
outburst is occurring simultaneously with the optical and infrared
eruption demonstrates that in at least some cases, the X-ray emission is
due to matter accreting onto the star.
> http://SkyandTelescope.com/news/article_1327_1.asp
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HIGHLIGHTS OF THIS WEEK'S SKY
* Full Moon on Sunday, August 29th.
* Venus (magnitude -4.2, in Gemini) shines brightly high in the east
before and during dawn -- the bright Morning Star.
* Uranus is at opposition (opposite the Sun in our sky) on Friday, August
27th.
For details, see This Week's Sky at a Glance and Planet Roundup:
> http://SkyandTelescope.com/observing/ataglance/
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