NASA Says Comet Fragments Won't Hit Earth

Hubble's Advanced Camera for Surveys took images of the disintegration of Comet 73P/Schwassmann-Wachmann 3's Fragment B. CREDIT: NASA, ESA, H. Weaver (APL/JHU), M. Mutchler and Z. Levay (STScI).

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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