Previous Topic :The Solar System
The Shape Of The Earth And Its Proofs
From years of accumulated knowledge experience and observations in different part of the world, it is known that the earth is spherical in shape not flat.
It is slightly flattened at the pole, hence the earth is not perfectly spherical.
The shape of the earth is more accurately referred to as a Geoid [The Earth shape].
Evidence Of The Earth Sphericity
There are many ways to prove that the earth is spherical in shape, these proves are;
Circumnavigation Of The Earth
1] Circumnavigation of the earth : Ferdinand megallian, a Spanish sailor with his crew sailed round the earth between 1519 and 1522, he and his crew were the first people to do so,
If the earth is flat, he and his crew would have fallen off the flat edge but instead they sail round the spherical edge because if the earth is truly flat, Ferdinand and his crew would have fell off the flat edge. Also modern air routes and area navigation are based on the assumption that the earth is spherical in shape.top↑
2] The circular horizon : when one view a distance horizon from the deck of a ship at a sea or from a cliff, the land and everywhere always look circular in shape with increase attitudes (height) which suggests that the earth is spherical in shape.
Sunrise And Sunset
3] Sunrise and Sunset : As the earth rotates from west to east, place in the east experience the sun (earlier sunrise) than place in the west and also place in the west see the sun later (sunset) than place in the east.
If the earth is flat, then the whole earth should experience sunrise and sunset at the same time, but instead sun rise and set at different time for different place.top↑
4] Ship Visibility : as a ship approaches the harbour, only the top of the mast is seen first before the hill, and also the same when it leaves the harbour, it disappearance over the curved surface is equally gradual. If the earth were flat, the entire body of the ship will be seen or observe all at ones because if the earth were flat the surface of the earth will also be flat.
Sphericity Of Planetary Bodies
During Pole Of Equal Length On The Earth
6] During pole of equal length on the earth : when three poles of equal length are driven at the same depth into a level ground, the centre pole were found to be slightly projected above the other pole at either side because of the round curvature of the earth.
If the earth were flat, all three poles should have the same height.
8] Aerial photograph : when a picture of the earth is taken from a high altitude by rockets or drones, the picture clearly show the curved edge of the earth.
This proof is the most recent proof of the sphericity of the earth.
Movement Of The Earth
Earth movement : the earth moves in space in two distinct ways, these two distinct ways are;
2] The Earth also revolves round the sun in an orbit once in every 365¼ days causing the seasons and the year.
Rotation Of The Earth
1] The earth rotates or moves on its axis from west to east.
2] The rotating earth is inclined at an angle of 23 1/3° along its axis.
3] It takes the earth 24 hours, that is, a day to complete one rotation.
Meaning, the earth rotates through 360° in every 24 hours.
4] The rotation of the earth causes day an night.top↑
5] There are 24 hours in a day, hence, there are 12 hours of day light and 12 hours of darkness.
6] The earth rotates through 15° in 1 hour and rotate through 1° in 4 minutes.
The sun does not move but it appears as if the sun is moving, sometimes the sun disappears completely which is called the apparent movement of the sun
Effects Of Rotation Of The Earth
1] Day and night : as the earth rotates on its axis, only one part of the earth faces the sun at a time and receives day light from the sun while the other part of the earth backing the sun rays will experience total darkness.top↑
2] Time difference from place to place : The earth rotates through 360° in every 24 hours and every 1 hour the earth rotates through 15°, therefore, generally there is a time difference of 1 hour for every 15° of longitude when some people are experiencing sunrise, other are experiencing sunset, noon and other midnight.
3] Deflation of rain and ocean current : due to the rotation of the earth, freely moving bodies on the surface of the earth are deflected from their original path to the right in the northern hemisphere or to the left in the southern hemisphere.top↑
4] Daily rising and falling of the tides : the earth rotates explain the gravitational pull exerted by the sun and the moon, causing daily rising and falling of the tides.
The fifth one is , dawn and twilight, I believe I have explain what a dawn and what a twilight is? But if you are new to this session, here is the link to the session The Solar System, there you will see everything, till next class guys.
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