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
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.
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