Earth Fact File

There are three key features that distinguish Earth from any other planet we have discovered, these are:

 

 

1.Its atmosphere is composed of mainly oxygen and nitrogen. Water is present in its 3 states, liquid water covering roughly 70% of the Earth’s surface. It is home to life in all its diverse forms

 

2. Contrary to popular belief, the Earth is not spherical, as it is flattened at the poles by 42km, making it an oblate spheroid. Although there are still a small amount of people who believe the Earth is flat, there is a completely overwhelming amount of evidence that proves that it is spherical. A few of the reasons are 

 

• Ships disappear over the horizon 
• Satellites orbit the Earth – impossible if it was flat 
• The curvature of the Earth’s shadow is visible during a partial lunar eclipse 
• We have pictures

3. The Earth’s polar axis is titled by 66.5 degrees to the plane on which it orbits the sun (the ecliptic plane). This means the sun lies directly above the equator on only two dates of the year – the spring and autumnal equinoxes. These occur on the 21st of March and the 22nd/23rd of September.

 

 

Astronomy Definitions

 ·         Oblate Spheroid- A sphere that is slightly flat on both poles due to the earth’s rotation. Spinning on its north-south axis.


·         Poles- they are two opposite points on a planet’s surface through which the planet’s axis passes.

Solar system- A system consisting of a group of planets or other bodies that orbit a star.

Solar System
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Horizon- the horizon is a point of apparent intersection between the land/sea and the sky as seen by the observer.

Horizon
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Latitude- the angular distance of a place north or south of the earth’s equator usually expressed in degrees.



Equinox-The date or time when the sun is directly above the equator, this is when both day and night are equal length.

Equator-Is an imaginary line on a planet that is equal distance from both poles. It divides the planet into the northern and southern hemisphere.

 The Ecliptic- Is the plane on which the earth orbits the sun. The earth's polar axis is tilted by 66 and a half degrees to reach this plane.