[meteorite-list] NASA Says Comet Fragments Won't Hit Earth

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Sun Apr 30 13:41:12 2006
Message-ID: <200604281927.MAA17896_at_zagami.jpl.nasa.gov>

http://www.space.com/scienceastronomy/060427_cometsw3_noimpact.html

NASA Says Comet Fragments Won't Hit Earth
By Tariq Malik
space.com
27 April 2006

Chunks of a comet currently splitting into pieces in the night sky will
not strike the Earth next month, nor will it spawn killer tsunamis and
mass extinctions, NASA officials said Thursday.

The announcement, NASA hopes, will squash rumors that a fragment of the
crumbling Comet 73P/Schwassmann-Wachmann 3 (SW 3) will
slam into Earth just before Memorial Day.

"There are some Internet stories going around that there's going to be
an impact on May 25," NASA spokesperson Grey Hautaluoma, told SPACE.com.
"We just want to get the facts out."

Astronomers have been observing 73P/Schwassmann-Wachmann 3, a comet that
circles the Sun every 5.4 years, for more than 75 years and are
confident that any of the icy object's fragments will remain at least a
distant 5.5 million miles (8.8 million kilometers) from Earth - more
than 20 times the distance to the Moon - at closest approach between May
12 and May 28.

"We are very well acquainted with the trajectory of Comet 73P
Schwassmann-Wachmann 3," said Donald Yeomans, manager of NASA's
Near-Earth Object Program Office, in a written statement. "There is
absolutely no danger to people on the ground or the inhabitants of the
International Space Station, as the main body of the object and any
pieces from the breakup will pass many millions of miles beyond the Earth."

The main SW 3 fragment, dubbed Fragment C, will make its closest pass by
Earth on May 12 at a safe distance of 7.3 million miles (11.7 million
kilometers), NASA said, adding that skywatchers will be able to use
small telescopes to spot the comet chunks by scanning the
constellation Vulpelca during the early-morning hours. [Click here
<http://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=060414_comet_map_02.jpg&cap=Sky+Map%3A+The+positions+of+comet+SW-3+at+one-week+intervals+as+of+1+a.m.+local+time+from+mid-northern+latitudes.>
for a map of SW 3's path across the sky.]

NASA's Hubble Space Telescope and other instruments have been
watching SW 3's disintegration. The comet's numerous fragments stretch
across several degrees of the night sky. For comparison, the Moon's
diameter covers about one-half a degree in the sky.

"Catastrophic breakups may be the ultimate fate of most comets,"
explained Hal Weaver, a planetary astronomer of the Johns Hopkins
University Applied Physics Laboratory, in a statement.

Weaver led a team of researchers during the Hubble observations of SW 3,
and used the space telescope to study the break up of comets
Shoemaker-Levy 9 - which was ripped apart by Jupiter?s gravity and hit
the giant planet between 1993 and 1994 - Hyakutake in 1996, and 1999 S4
(LINEAR) in 2000, NASA said.

Hubble's new SW 3 observations suggest that chunks of the comet are
pushed behind its tail by the outgassing of Sun-facing pieces. Smaller
pieces appear to be ejected from their nucleus faster than their larger
brethren, while other fragments seem to simply fade away.

When set alongside studies by other observatories, Hubble's images may
help astronomers determine what is causing the comet's disintegration as
it nears the Earth and Sun, the space agency added.

German astronomers Arnold Schwassmann and Arno Arthur Wachmann first
discovered the SW 3 comet in 1930 while hunting for asteroids. Despite
its relatively short orbital period, the icy object was not seen again
until 1979, and then was missed during a 1985 pass.

Since then, however, astronomers have kept a close eye on SW 3 and in
1995 observed its initial break up.

Aside from a great sky show, the comet poses no danger to Earth and its
inhabitants, NASA officials said.
Received on Fri 28 Apr 2006 03:27:59 PM PDT