Download Earth`s Shape

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project

Document related concepts

Theoretical astronomy wikipedia , lookup

Astrobiology wikipedia , lookup

Timeline of astronomy wikipedia , lookup

Rare Earth hypothesis wikipedia , lookup

Impact event wikipedia , lookup

Geocentric model wikipedia , lookup

Extraterrestrial life wikipedia , lookup

Astronomy on Mars wikipedia , lookup

Astronomical unit wikipedia , lookup

Comparative planetary science wikipedia , lookup

Dialogue Concerning the Two Chief World Systems wikipedia , lookup

Transcript
Aim: What is the shape of the Earth?
I. Shape of the Earth
A. The Earth is NOT a perfect sphere, but it is
close!!!!!
B. Oblate spheroid – the true shape of earth in
which its equatorial diameter is slightly larger than
its polar diameter.
1. Polar Diameter (measured from N.Pole to S.
Pole) – 12,714 Km
2. Equatorial Diameter – 12,757 Km
N Polar Diameter
Equatorial Diameter
S
C. Evidence of Earth’s Shape
1. Photographs of Earth from outer space show that
Earth is round
2. Years ago, sailors noticed that ships slowly
disappeared or appeared over the horizon.
3. Gravity measurements
a. Gravity is the force of attraction between any two
objects.
b. The Law of Gravitation – the gravitational force is
proportional to the square of the distance between the two
centers of attracted objects.
Gravitational
Force
Distance Between two objects
c. If Earth was a perfect sphere, then the force of gravity
would be the same anywhere on the surface. But, the force of
gravity is actually greater at the poles than at the equator.
Thus, the distance from the poles to the center of the Earth is
less than the distance from the equator to the center of the
Earth!!!!!
4. Altitude of Polaris (North Star)
a. The altitude (height or angle made between the observer’s eyea
and the observer’s horizon) of Polaris is equal to the observer’s
latitude (only in the northern hemisphere).