Source: The Mercury, 13 March, 1998, p.1


Space
rock
closes
in on
Earth

AN asteroid 1.5km
wide is heading for
Earth-and is due to
arrive on October
28, 2028.

   Scientists say the
chances of the
massive chunk of
space rock colliding
with Earth are tiny.
But uncertainties in
the measurements of
its orbit mean
scientists cannot
rule out a collision.

   They certainly
expect it to come
closer than the-
Moon which is
about 386,000km
away.

   In fact, their best
estimate is that the
asteroid will whiz
by at a mere
42,000km.

   Astronomer- Dan
Green, of the
Harvard-
Smithsonian Centre
for Astrophysics in
Cambridge,
Massachusetts,
admitted: "Right
now one has to say
that Earth is within
the error bars."

   This asteroid is
not as large as the
one scientists
believe hit Earth 65
million years ago,
killing two-thirds
of all life, including
the dinosaurs.

   But it is thought
to be the largest
object known in
human history to
have passed

Continued Page 2

Asteroid on collision
course with Earth

FROM PAGE 1

this close to Earth.

   The asteroid, designated 1997
XF11, was found in December
and its newly calculated orbit
was announced yesterday in the e-
mail version of the International
Astronomical Union Circular.

   There is no internationally
adopted plan for what to do if an
asteroid is seen on a collision
course with Earth.

   Many astronomers and space
enthusiasts have come up with
detailed proposals in the past,
ranging from zapping an
approaching asteroid with a
laser beam to blowing it up with
nuclear explosives.

   An asteroid 1.5km across
could strike Earth with enough
force to wipe out a quarter of the
human population say
scientists.

   Most of the damage wouldn't
come from the impact itself but
from the dust that would be
kicked up into the atmosphere,
blocking the planet from the
sun's warmth.

   Odds are that an impact of that
size occurs about once every
300,000 years.

   Right now, the asteroid is
moving away from Earth about
80,500km/h.

   Scientists already know that
on October 31, 2002, the
asteroid will take an early swing
by Earth at a safe distance of 9.6
million km.

   Astronomers are now
planning more observations of
1997 XF11, and are looking to
see whether the asteroid shows
up on older photographs of the
sky.

   "The accuracy and precision of
that orbit should improve every
time we find something," said
Eleanor Helin of NASA'S Jet
Propulsion Laboratory in
Pasadena, California. Ms Helin
heads another project to locate
and track near-Earth objects.

   Any new observations would
help, but it would take some
time for astronomers to calculate
the precise orbit.

   The closest recorded asteroid-
Earth encounter occurred on
December 9, 1994, when a very
small asteroid passed within
about 105,000km.

   There are several groups of
scientists now working to find
and follow objects that could
one day threaten Earth.


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