Chapter 4 Notes Place these notes in your Notebook. Slide 2
Scientists think our solar system formed out of a great cloud of
collapsing gas and dust. Earths original surface is thought to have
been cratered like the moon. Approximately 70 percent of the Earths
surface is covered with water. Slide 3 The Earths shape is slightly
flattened at the poles and slightly bulging at the equator. The
Earths 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 Slide 4 The approximate
temperature of the Earths inner core is 6000 Kelvin. The Earth
turns on its axis. Earth moves around the sun in a single plane.
Earths axis is slightly tilted. Slide 5 Slide 6 Slide 7 Earths
orbital plane is almost a perfect circle, however it is slightly
skewed. Slide 8 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 Earths rotation. Slide 9 In the middle of the
beautiful entrance hall of the Steno Museum you can see a version
of the French physicist, Lon Foucault's (1819-68) famous pendulum
experiment. Foucault in Pantheon, Paris Slide 10 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. Slide 11 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. Slide 12 Click the Earth to observe evidence
of Earth turning about an axis. Slide 13 Slide 14 During an
earthquake in Pymatuning, PA in 1998, a Foucault's pendulum acting
as a seismoscope scribed this incredible work of earthquake art.
Slide 15 Coriolis effect, length of day, and direction of sunrise
are all a direct result of Earths rotation. Seasons are caused by
the Earths elliptical orbit around the Sun. Slide 16 Slide 17
Earths 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. Slide 18 The approximate location of the
International Date Line is the 180 th 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 Earths seasons are
caused by revolution of Earth around the sun and tilt of Earths
axis. Slide 19 Earths 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. Slide 20 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 Earths
surface. Slide 21 Essay Earth has slowly been losing heat since its
formation. Discuss the reasons why heat loss varies over Earths
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. Slide 22 Essay
Every fourth year, the calendar year is 366 days long. Using your
knowledge of Earths 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.
