03 February, 1998. The once-clear distinction between comets and
asteroids has become somewhat blurred. An asteroid, a solid body
with no tail, has been seen coming in from the Oort comet cloud,
while some bodies that seem to be asteroids are probably dead
comets. The asteroid may have been kicked out of the asteroid belt by Jupiter.
The asteroid Mathilde, recently observed by the NEAR
spacecraft, has a very low density, only 1.5 grams per cubic
centimeter, the density and its darkness more typical of a comet
than a rocky asteroid. It may, however, be a rubble-pile of fused
asteroidal debris created in an ancient impact.