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(meteorobs) Sky & Telscope News Bulletin - November 20, 1998
SKY & TELESCOPE'S NEWS BULLETIN
NOVEMBER 20, 1998
LEONIDS AFTERMATH
It seems that this past week's Leonid meteor shower peaked a little ahead
of schedule. Initially predicted to reach maximum at 19:43 Universal Time
on November 17th -- when the Earth crossed the orbit of parent comet
55P/Tempel-Tuttle -- the highest rates apparently came about 15 hours
earlier. European observers may have had the best of it as dazzling
fireballs came every few seconds -- sometimes several at the same time.
Based on dozens of reports from observers throughout the United States,
meteor watchers under clear skies were not disappointed on the night of
November 16-17, but rates were markedly lower the following night. No
damage to Earth-orbiting satellites has been reported.
How will the showing of Leonids this year affect astronomers predictions
for 1999? As Donald K. Yeomans (Jet Propulsion Laboratory) told *Sky &
Telescope*: "My prediction for 1999 won't change but I suspect the dust
particle cloud modelers will revise their predictions somewhat. If nothing
else, an early arrival of the Leonid 'peak' (if that indeed turns out to be
the case) shows how difficult it is to predict a very complex process --
rather like trying to predict the weather a year in advance."
The next major meteor shower is the Geminids. See the December issue of
*Sky & Telescope* for details.
A PIECE OF THE DINOSAUR KILLER
A University of California geochemist may have discovered a chunk of the
impactor that scientists believe snuffed out 70 percent of the species of
life on Earth 65 million years ago. Frank T. Kyte writes in the November
19th *Nature* of a 2.5-millimeter-wide fossil meteorite extracted from the
clay at the bottom of the Pacific Ocean. Found in the sediments dating back
to the Cretaceous-Tertiary boundary, Kyte maintains that the pebble is a
piece of an asteroid that struck the Yucatan Peninsula. His analysis
revealed that the fragment could very well have originated as a
carbonaceous chondrite, not interplanetary dust nor cometary material.
COMETARY OUTBURST
Although far from being another Hale-Bopp or Hyakutake, Comet C/1998 U5
(LINEAR) has been putting on a surprisingly good show. Discovered in late
October by MIT's Lincoln Laboratory Near Earth Asteroid Research (LINEAR)
Team and later identified as a comet by team member Frank Shelly, it was
not expected to brighten beyond magnitude 10.5. To the surprise of all, the
comet underwent an outburst in the second week of November that brought
this fast moving object within the range of small telescopes and
binoculars. *Sky & Telescope* contributing editor and veteran comet
observer John Bortle put the comet's magnitude at 8.2 and measured a coma
diameter of 9 arcminutes for the night of November 13th. This made LINEAR
the brightest comet in the sky, a shade brighter than Comet
Giacobini-Zinner. The comet is still about magnitude 8.5. This week it
leaves Cassiopeia, runs through Andromeda, and enters Lacerta. Here are
positions for the coming week at 0:00 Universal Time in 2000.0 coordinates:
R.A. Dec.
November 21 0h 03m +55.9 deg.
November 23 23h 22m +51.9 deg.
November 25 22h 52m +47.7 deg.
IN SECOND PLACE, COMET GIACOBINI-ZINNER
Losing brightest-comet stature, Comet 21P/Giacobini-Zinner is crossing
northern Capricornus this coming week. It should be about as bright as it
will get, at a hair brighter than 9th magnitude. A medium-size telescope
will show it. For a finder chart, see page 107 of the November *Sky &
Telescope,* or visit
http://www.skypub.com/sights/comets/Giacobini/gz_1998.html. Here are
positions for Comet Giacobini-Zinner for the coming week:
R.A. Dec.
November 21 20h 29m -13.9 deg.
November 23 20h 40m -14.8 deg.
November 25 20h 50m -15.7 deg.
[snip]
===========================================================================
Copyright 1998 Sky Publishing Corporation. S&T's Weekly News Bulletin and
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