Transcript 1B (web) - Atascadero High School

California Earth Science
Standards
Section B
Students know that
evidence from Earth
and moon rocks
indicates that the solar
system was formed
from a nebular cloud
of dust and gas
approximately 4.6
billion years ago.
Please add the following
terms to your Standard 1
vocabulary booklet.
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Radioactivity
Nucleosynthesis
Lunar
Supernova
Accrete
Radioactivity the process by
which an unstable atom loses
energy by emitting particles.
Definition:
Similar words: radio, radiology,
radiation, radio waves.
Nucleosynthesis Definition: the
process of
creating new atoms from
pre-existing ones.
Similar words: mononucleosis,
photosynthesis, synthetic
Supernova the explosion
of a massive star at
the end of its lifespan.
Definition:
Similar words: Superman, noval
Accrete to make or
become bigger, as by
addition to.
Definition:
Similar words: concrete
Lunar Definition: Pertaining
to the
moon.
Similar words: La Luna, lunatic, lunar
eclipse
Since the 1800s, scientists have
known that Earth is very old by
using relative dating techniques.
Relative dating techniques do not
provide an exact age, but give us
an idea of which events had to
occur before others could take
place.
Then in the 1900s, the discovery
of radioactivity provided science
with a “clock. ”
This method
now allows us
to determine
the age of
materials from
the deep past.
For instance, based upon
radioactive dating, we know that
Morro Rock is approximately 20
million years old.
When we examine the oldest rocks
from the Earth, (as well as those
brought back from the Moon and
meteorites from space) we have
concluded that the age of the entire
solar system is 4.6 billion years old.
Section 1A suggests that our solar
system formed from a nebula.
So … where do nebulas come from?
Evidence suggests that the entire
universe once started at a single
point and has been expanding ever
since. This is known as the “Big
Bang Theory.” It will be discussed
later in Standard 2.
According to this theory, most of
the original material in the universe
was Hydrogen and Helium. But …
… eventually heavier elements
came into existence through a
process called nucleosynthesis.
This occurs within the cores of
massive stars.
When some stars come to the end
of their “life cycle,” they result in an
explosion known as a supernova.
This spreads all the material they
have created back into space.
Strong evidence suggests that our
own solar system arose from a
nebula that, in turn, was formed
from a nearby supernova.
So, what caused our solar system
to take on its present
characteristics?
You should already know that a
nebula is a slowly rotating cloud.
Over time, the forces of gravity will
pull it together.
So, imagine a rotating nebula as …
getting smaller, becoming warmer,
spinning faster, flattening out, and creating
clumps that would become planets.
Scientists believe that this is how our solar
system formed. The final major step was
for our sun to begin fusion.
A
B
Prepare to answer the following
multiple choice questions:
C
D
If spinning objects become
smaller, what happens to
their speed?
A. they spin faster
B. they spin slower
C. they stay the same
D. they disappear
If spinning objects spin
faster, what happens to
their shape?
A. they form into a ball
B. they form into a cube
C. they flatten out
D. they become taller
Complete the Play-Doh activity.
Watch the following movie:
So, imagine our rotating nebula as
getting smaller, becoming warmer,
spinning faster, and flattening out.
our own solar system.
So, imagine our nebula as spinning
faster while it is getting smaller.
our own solar system.
If you don’t already know the
answer, here are some hints:
What happens when you are
spinning on a swing and you pull
your legs together?
What happens to the shape of
objects as they spin faster?
• http://www.metacafe.com/watch/1111454/f
ormation_of_the_solar_system_great_ani
mation/
Have you ever watched someone
make pizza dough?
Since the nineteenth century, geologists, through the use of relative dating
techniques, have known that Earth is very old. Relative dating methods, however,
are insufficient to identify actual dates for events in the deep past. The discovery of
radioactivity provided science with a “clock.” Radioactive dating of terrestrial
samples, lunar samples, and meteorites indicates that the Earth and Moon system
and meteorites are approximately 4.6 billion years old.
The solar system formed from a nebula, a cloud of gas and debris. Most of this material consisted of
hydrogen and helium created during the big bang, but the material also included heavier elements formed
by nucleosynthesis in massive stars that lived and died before the Sun was formed. The death of a star
can produce a spectacular explosion called a supernova, in which debris rich in heavy elements is ejected
into space as stardust. Strong evidence exists that the impact of stardust from a nearby supernova
triggered the collapse of the nebula that formed the solar system. The collapse of a nebula leads to
heating, an increase in rotation rate, and flattening. From this hot, rapidly spinning nebula emerged the
Sun and solid grains of various sizes that later accreted to form objects that evolved through collisions into
planets, moons, and meteorites. The nebula from which the Sun and planets formed was composed
primarily of hydrogen and helium, and the solar composition reflects this starting mixture. The nebula also
contained some heavy elements. As the nebula cooled, condensation of the heavy elements and the loss
of volatile elements from the hot, inner nebula led to formation of rocky inner planets. To varying extents,
the whole of the solar system was fractionated; but the portion of the solar nebula now occupied by the
inner planets was highly fractionated, losing most of its volatile material, while the outer portion (beyond
Mars) was less fractionated and is consequently richer in the lighter, more volatile elements.
If spinning objects become
smaller in size, yet still have
the same mass, what happens
to their density?
A. They become more dense.
B. They become less dense.
C. They stay the same.