Chapter 2 Notes:

Unit I: Earth’s Shape and Size

Earth is a sphere

- The mast of a ship is the first to appear on the horizon

- North Star rose higher in the sky as a ship sails northward.

- Earth’s round shadow falls on the moon during a lunar eclipse.

- Photographs of the earth have been taken from spacecraft.

Earth is not a perfect sphere

- The mass of an object changes with locations around the earth.

- Circumference of the earth is longer around the equator than the measurement from around the poles.

- Diameter of the earth is longer across the equator than the measurement from across the poles.

- Earth is classified as an Oblate Spheriod

How to measure Earth’s circumference

- Eratosthenes’s method

- Angle divided into 360 degrees

- Value multiplied by distance between two points

Earth’s dimensions

circumference at the equator

= 40,074 kilometers

circumference at the poles

= 40,007 kilometers

diameter at the equator = 12,756 kilometers

diameter at the poles = 12,714 kilometers

surface area = 510 million square kilometers

29% land mass

71% water surface

 

Unit II: Earth’s Density and Temperature

Density:

- a measure of the amount of material in a given space.

Density = mass / volume or D = m / V

Earth’s average density is 5.5 grams per cubic centimeters

- Crust is only 2.8 g/cm3

- Core is about 8.0 g/cm3

Temperature:

- Changes throughout the earth

- Temp. remains constant to a depth of 20 meters

- Temp. rises 1 degree for every 40 meters in depth

- Earth’s estimated inner core temperature is about 7000° C

What creates a hot crust?

- Radioactive material fond throughout the crust

- Friction caused from moving rocks in the crust