terms below that are printed in
are meant to catch your attention, and you will note
that most of them are nouns.
In science nouns are necessary, but verbs—the
of the earth—are
more important and these will be emphasized in Quiz 1.
The quiz will be a mixture of very easy, to a
few quite challenging questions.
The more difficult questions will ask you to take something you
already know and put the pieces of information together to come up with a conclusion.
ORIGIN OF THE SOLAR SYSTEM
Our own sun is a typical star within the Milky Way, a
2 x 10
consisting of diffuse dust and gas within the galaxy, begins to collapse.
is due to the force of gravity, which causes all particles that have mass to be mutually attracted to one
another, and collapse is assisted slightly by the pressure of starlight.
As shrinkage continues, the cloud
breaks up into a swarm of smaller clouds, each destined to become a star.
early stage of star formation; it consisted of a central "bulge" surrounded by a rotating flattened disk,
which itself sustains complex internal motions of dust and gas.
Planets, their moons, etc. condensed
from the solar disk, and the sun condensed from the central bulge.
Thus the sun and planets, their
moons, asteroids, comets, meteorites, etc.—the entire
—formed together, at the same time
from the same material.
—Mercury, Venus, Earth, and Mars—are relatively small, dense bodies with small
(liquids, gases at room temperature).
Beyond the orbit of Mars there is
a large gap populated by thousands of small objects, the
, and beyond the asteroids come the
orbits of the
Jupiter, Saturn, Uranus, and Neptune.
(Outermost Pluto, formerly regarded
as a planet, has been demoted to “dwarf planet” status.)
Outer planets, known as “gas giants,” are of
low density; they consist mostly of volatile substances and are relatively large bodies.
We postulate that
early in the development of the solar system, the proto-sun heated up and drove away a large amount of
gas in its near vicinity, leaving inner planets as small bodies consisting chiefly of rock and metal.
planets survived with less loss of material, and therefore they have a more sun-like composition today.
The earth consists of a metallic
16% of its volume) overlain by a
83%) consisting of
dark, dense rock.
At the surface, the earth’s
(<1%) consists of a great variety of rock types, and it
conceals the mantle almost everywhere.
Initially the earth must have been composed of a mixture of metal and rocky material.
Sources of heat,
such as radioactive decay, caused early melting of material with the lower melting point, which was the
Dense liquid metal filtered downward to form the core, while less dense rocky material floated