Chapter 4 Notes
Place these notes in your
Notebook.
Scientists think our solar system formed
out of a great cloud of collapsing gas
and dust.
Earth’s original surface is thought to have
been cratered like the moon.
Approximately 70 percent of the Earth’s
surface is covered with water.
The Earth’s shape is slightly flattened at
the poles and slightly bulging at the
equator.
The Earth’s imperfect shape is primarily a
result of its spinning motion.
The following are sources of heat when
the Earth first formed:
• Compression by overlying materials
• Bombardment by meteorites
• Decay of radioactive isotopes
The approximate temperature of the
Earth’s inner core is 6000 Kelvin.
The Earth turns on its axis.
Earth moves around the sun in a single
plane.
Earth’s axis is slightly tilted.
Earth’s orbital
plane is almost a
perfect circle,
however it is
slightly skewed.
Because the Earth is
not a perfect sphere
an object weighs
less at the equator
than at the poles.
A Foucault pendulum
provides evidence of
Earth’s rotation.
Foucault in Pantheon, Paris
In the middle of
the beautiful
entrance hall of
the Steno
Museum you
can see a
version of the
French
physicist, Léon
Foucault's
(1819-68)
famous
pendulum
experiment.
This is Foucault's
Pendulum. It was
used as evidence that
the earth was rotating
and thus placed in the
center of the (then
named) Temple for
Science and Reason
as a testament to the
success of science in
explaining the natural
world.
Starting the
Foucault
Pendulum in
the building
of the
National
Academy of
Sciences and
the National
Research
Council at
Washington;
this
instrument
demonstrate
s the rotation
of the earth.
Click the Earth to
observe evidence of
Earth turning about
an axis.
During an
earthquake in
Pymatuning, PA
in 1998, a
Foucault's
pendulum acting
as a
seismoscope
scribed this
incredible work of
earthquake art.
Coriolis effect, length
of day, and direction
of sunrise are all a
direct result of
Earth’s rotation.
Seasons are caused
by the Earth’s
elliptical orbit around
the Sun.
Earth’s greatest speed of rotation occurs
at the equator.
Two locations separated by 1 degree of
longitude differ in solar time by 4
minutes.
The number of worldwide standard time
zones is 24.
Travelers crossing the International Date
Line change their calendar by one day.
The approximate location of the International
Date Line is the 180th meridian.
Parallax of nearby stars provides evidence
that Earth moves around the sun.
Earth is closest to the sun on or about
January 2.
The Earth’s seasons are caused by
revolution of Earth around the sun and tilt
of Earth’s axis.
Earth’s rate of revolution is very close to 1 degree
per day.
1 degree per day would give us a 360 day year.
We actually have closer to 365.25 days in a year.
A: Inner core
Solid iron and nickel
B: Outer core
Liquid iron and nickel
C: Mantle
Solid of iron, silicon, and
magnesium with liquid properties.
D: Crust
Thin, rigid layer of lighter rocks.
Includes the Earth’s surface.
Essay
Earth has slowly been losing heat since its
formation. Discuss the reasons why heat loss
varies over Earth’s surface.
Some rock types lose heat more quickly than
others.
The thickness of the crustal rock varies from
place to place.
The percentage of radioactive material in rocks
varies.
Essay
Every fourth year, the calendar year is
366 days long. Using your knowledge of
Earth’s revolution , explain why such a
leap year is necessary. What would
happen to the calendar compared to the
seasons if leap years were not
observed?
Earth revolves around the sun in a little
more than 365 days. The extra partial
day would add up over time, causing
the seasons to gradually shift dates.