THE SOLAR SYSTEM
▲ Meteor Crater in Arizona,
USA, photographed from the
air. This is the most famous
of all impact structures,
though not now the largest
one to be found. It is also
known as Barringer Crater.▼ Gosse’s Bluff, Northern
Territory of Australia;
photograph by Gerry
Gerrard. Its impact origin
is not in doubt, but it is
very ancient, and has
been greatly eroded.SOME IMPORTANT METEORITIC CRATERS
Name Diameter, Date of
m discovery
Meteor Crater, Arizona 1265 1871
Wolf Creek, Australia 675 1947
Henbury, Australia 200 110 1931 (13 craters)
Boxhole, Australia 175 1937
Odessa, Texas, USA 170 1921
Waqar, Arabia 100 1932
Oesel, Estonia 100 1927geology, and the form is not characteristic of collision.
Note also that no crater is associated with the giant Hoba
West Meteorite.
It has often been suggested that the Earth was struck
by a large missile 65 million years ago, and that this caused
such a change in the Earth’s climate that many forms of life
became extinct, including the dinosaurs. It has been claimed
that the buried Chicxulub impact crater in the Yucatan Penin-
sula, Mexico, was the result of the meteorite fall which killed
the dinosaurs.
No doubt further craters will be formed in the future;
there are plenty of potential impactors moving in the closer
part of the Solar System. Although the chances of a major
collision are slight, they are not nil, which is partly why
constant watch is now being kept to identify wandering
bodies. It is even possible that if one of these bodies could
be seen during approach, we might be able to divert it by
nuclear warheads carried on ballistic missiles – though
whether we would be given enough advance warning is
problematical.
In January 2000, the British government set up a
special committee to look into the whole question of
danger from asteroidal or cometary impact. If there is
such an impact, let us hope that we cope with the situation
better than the dinosaurs did.D108-151 UNIVERSE UK 2003CB 7/4/03 5:20 pm Page 151