|It is known that there are small asteroids with
very irregular shapes. What are the forces that
give these asteroids their shapes? What shape do
you think a neutron star that does not rotate
around its axis can have?
|Question Date: 2004-04-15|
The force that tends to make objects spherical is
gravity. In the absence of gravity, there is no
preference for shapes, so objects will be in any
shape. Larger bodies exert more gravity, and so
tend more to be round.
Neutron stars, short of
black holes, are the most strongly gravitationally
bound objects in the universe. In black holes, all
of the mass is contained in a single point with no
volume. Thus, neutron stars,which still have
finite volume, are also the most perfectly
spherical objects in the universe.
Most astronomers think that asteroids are failed
planets, which is to say that they are leftover
rock from the birth of the solar system that never
stuck together to form into planets.While the
question of irregular shapes can be answered in
various ways (with various levels of scientific
jargon), the basic reason is that the asteroids
are too small(most are under 200km) for gravity to
be able to deform them into spherical shapes. The
strength of the rock is stronger than the strength
Actually, saying that asteroids
are too "small" may not be the right way to phrase
it, since this also depends on density. Neutron
stars are often only about 20km in diameter, but
have a mass of almost1.5 times the mass of the
Sun. (They are the densest known objects, in
fact.) Because neutron stars are such extremely
massive objects,compressed to such a high density
and bound by a gravitational force,they would be
round in the absence of rotation.
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