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  • Frits Westra
    By Toutatis! Monster asteroid flyby excites doomsters, skygazers Sun Sep 26,12:16 AM ET PARIS (AFP) - On Wednesday, Earth will get its closest known shave this
    Message 1 of 1 , Sep 28, 2004
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      By Toutatis! Monster asteroid flyby excites doomsters, skygazers

      Sun Sep 26,12:16 AM ET

      PARIS (AFP) - On Wednesday, Earth will get its closest known shave this
      century from a major asteroid, a monster big enough to extinguish billions
      of lives were it ever to collide with our home.

      But, in contrast to the warnings of a handful of doomsayers, scientists
      say the peril from this rock is beyond negligible.

      In fact, they say this particular risk is zero and will remain so for
      several centuries, thanks to an increasingly successful effort to spot
      space bruisers and calculate their future orbits around the Sun.

      The asteroid in question is 4179 Toutatis, a behemoth some 4.6 kilometers
      (2.9 miles) long by 2.4 kilometers (1.5 miles) across.

      Spinning like an anarchic dumbbell, Toutatis will be at its closest to
      Earth at 1337 GMT on Wednesday, when it will be 1,549,719 kilometers
      (962,951 miles) away, according to the Near-Earth Object (NEO) Programme
      run by NASA (news - web sites)'s Jet Propulsion Laboratory (JPL).

      That may seem comfortingly far.

      But in galactic terms it is narrower than a whisker: just four times the
      gap between Earth and the Moon.

      Six months ago, panicky rumours spread on the Internet that there was
      little point to booking next year's summer holidays -- that NASA had got
      it wrong or lied, and we were all heading for The Big One.

      Websites run by Christian zealots and individuals in contact with aliens
      predicted the Second Coming of Jesus or a secret US nuclear missile strike
      to neutralise the asteroid.

      True, Toutatis is so big and will be so close "it should be visible in the
      night sky in the Southern hemisphere, if you point a pair of binoculars in
      the region of ëthe starû Alpha Centauri," says Benny Peiser of
      Liverpool John Moores University and a fellow of Britain's Royal
      Astronomical Society.

      Were Toutatis to collide with Earth, the energy released would be
      equivalent to tens of thousands of hydrogen bombs, kicking up dust clouds
      which would shield out the sunlight, plunging the planet and its
      inhabitants into a lethal "impact winter."

      Earth's atmosphere protects us from NEOs up to a diameter of 40m (130
      feet), an impact energy of about three megatonnes.

      Beyond that size, the news is bad. NEOs between 40m and one km (0.6 of a
      mile) across can inflict local damage equivalent to thousands of nuclear
      bombs, as evidenced by the massive explosion in Tanguska, Siberia in 1908.

      The NEO that whacked into what is now Mexico 65 million years ago, ending
      the long reign of the dinosaurs, is estimated to have been between five
      and 15 kms (three and 9.5 miles) across, packing a 30- to
      100-million-megatonne punch.

      The good news, though, is that big advances are being made to spot the
      biggest threats.

      Spaceguard Survey, a US programme, is already two-thirds towards its goal
      of identifying by the end of 2008 90 percent of the estimated 1,000-1,100
      asteroid NEOs that are more than one km (0.6 miles) across -- the climate
      killers.

      That does not include, however, comets that take centuries to loop around
      the Sun and whose paths thus remain uncharted. Yet only a tiny number of
      these are likely to be any potential threat.

      "Any NEO that is going to hit the Earth will swing near our planet many
      times before it hits, and it should be discovered by comprehensive sky
      searches like Spaceguard," says NASA expert David Morrison.

      "In almost all cases, we will either have a long lead time," he points
      out, "or none at all."

      Asteroids are commonly thought of as chunks of rock left over from the
      formation of the Solar System 4.5 billion years ago.

      The vast majority safely trundle around the Sun in the asteroid belt
      between Mars and Jupiter.

      But the gravitational tug of giant planets such as Jupiter, as well as
      collisions with other asteroids, can nudge rocks out of the belt. Those
      whose orbits may regularly bring them close to Earth are classified as
      NEOs.

      Discovered in 1989, Toutatis is probably one of the most studied asteroids
      of all because its most recent circuits have brought it so close to Earth.
      It takes four years to loop around the Sun, although it has a very odd,
      almost chaotic spin quite unseen in any other asteroid.

      It has not been so close to Earth since 1353 and won't be this close again
      until 2562, says the specialist website space.com.

      Toutatis owes its name to a trio of French astronomers, who baptised it
      after a Celtic god well-known in France for the comic book hero Asterix.

      Protected by Toutatis, Asterix and his friends fear nothing except the
      idea of the sky falling on their heads. On Wednesday, too, they should
      have nothing to worry about.

      Copyright © 2004 Agence France Presse.
      Copyright © 2004 Yahoo! Inc.
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