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Ärende: S&T's Weekly News B 02/0
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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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levels. If you're in the market for a new telescope, our expanded
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up to $5,000.

> http://SkyandTelescope.com/SkyWatch
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