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 more
important are the verbs—the
of the earth, and these will be emphasized in Quiz
The quiz will be a mixture of very easy, to a few quite challenging questions.
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
consisting of diffuse dust and gas within the galaxy, begins to
This is due to the force of gravity, which causes all particles having mass to be
mutually attracted to one another, and collapse is assisted slightly by the pressure of
As shrinkage continues, the cloud breaks up into a swarm of smaller clouds,
each destined to become a star.
represents an 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 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, Mars) are relatively small, dense bodies with
small quantities of
(liquids, gases at room temperature).
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,
(Pluto, the outermost 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, of more sun-like composition, survived with less loss of material.
The earth consists of a metallic
16% of its volume) overlain by a
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