Earths Motions
Earths PropertiesEvidence of Earths Shape
S
A line of sight is the straight, unimpeded path taken by light
from an object to an eye.
Objects appear to sink when they move across the ocean and slip
below the horizon on a curved surface.2Learning Targets
Earth is nearly a perfect sphere.3Earths Shape
Earth is an oblate spheroid.flattened at the poles.bulging at
the equator.
Due to its daily rotation, Earth bulges about 40 kilometers at
the equator.4Not a perfect sphere
Earth looks flat on its surface.5Not a perfect sphere
Still, Earth is so close to the shape of a sphere that from any
point in space it looks like a perfect sphere.6Oblate Spheroid
An oblate spheroid is a nearly perfect sphere.
7How do we know Earth is a round?
8Lets go sailing!
How did people more than 2000 years ago (14 centuries before
Columbus) figure out that Earth was round?
9Lets go sailing!
10Lets go sailing!
He noticed ships as they approached the horizon.The bottom of
the ship appears to sink into the ocean.This is because the Earth
is curved. 11Evidence of Earths Shape
Aristotle observed that Earth was a sphere a long time ago! FOSS
WEB
12What other evidence do we have to indicate we live on gigantic
sphere!
We have photographs of Earth taken from space
A lunar eclipse casts earths shadow on the moon. A curved shadow
is shown.
Changing positions of the sun and stars like Polaris in
reference to location.
13What other evidence do we have to indicate we live on gigantic
sphere!
We have photographs of Earth taken from space
A lunar eclipse casts earths shadow on the moon. A curved shadow
is shown.
Changing positions of the sun and stars like Polaris in
reference to location.
14What other evidence do we have to indicate we live on gigantic
sphere!We have photographs of Earth taken from space
A lunar eclipse casts earths shadow on the moon. A curved shadow
is shown.
Changing positions of the sun and stars like Polaris in
reference to location.
An imaginary line where the sky meets the Earth or the
Ocean.15What is a horizon?
16Debunking A Flat Earth
17Response Sheet investigation 2
18How do observations of ships at sea provide evidence of earths
shape?The horizon formed by the sea establishes a visual barrier
where it meets the sky.
Ships sailing beyond the horizon sail down the curvature of
Earth resulting in the illusion of ships sinking.
Ships on a flat Earth diminish in size but do not appear to sink
into the ocean.
19Just for Fun!
