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.

 

 

Earth's Atmosphere

Due to the increase in the different gasses in our atmosphere, the atmosphere is becoming more and more thinner and slowly merging with space at about 100 km. This boundary is known as the Stratosphere (Karman line). The atmosphere protects the earth from energetic X-rays as well as keeps the temperature at an average of 15 degrees. This is done by reflecting excess sunlight away from the earth.

BBC Bitesize

 

In basic terms the Earth's atmosphere protects the Earth from heating up and absorbing large amounts of different radiation such as x-rays, gamma rays etc. It also protects us from meteorites to an extent as when the meteorite enters the Earth's atmosphere most of the mass is burned reducing the size of the impact.
 

Gas:	Percentage in atmosphere:
Nitrogen	78%
Oxygen	21%
Argon	1%
Carbon dioxide (at present)	0.04%
Water vapour	1%

The layers of earth’s atmosphere

Earth has four layers in its atmosphere.

The troposphere is 12km up, this is the layer closest to the earth and where the weather occur (clouds). The air is the thickest here, its mass is about 80% of the total of all the layers of the atmosphere and most of the heat that comes from here is reflected back off the earth’s surface.

The stratosphere is the next layer, it goes to 50km up, and it has the ozone layer in it. Its pressure is 1/1000 of that at sea level.

Next layer is the mesosphere that is 80km up, this is the coldest layer at -100°C and has all the weather balloons in it and is where a lot of the meteoroids burn up because the density of air is just enough to start that happening.

http://en.wikipedia.org/wiki/File:Earth%27s_atmosphere.svg

The fourth layer and final is the thermosphere and the air is so thin that any change in heat is very extreme this why the temperature is very high, it can be 1500°C and goes all the way up to 350km above the earth’s surface. The aurora borealis also occurs in this layer. The exosphere is at the top of this layer. This is where the atmosphere begins to meet the vacuum of space and the international space station orbits here as well

The Earth's Atmosphere!

The Earth’s atmosphere

The Earth’s atmosphere is made up of 78% nitrogen, 21% oxygen, 1% argon 0.04%, carbon dioxide and 1% of other gasses for example helium, neon and methane. As your height increases the atmosphere gets thinner and thinner as it merges with outer space at approximately 10000 km above sea level. The Karman line is defined as the edge of space by astronauts and is about 100km above sea level.

What does the atmosphere do?

There are lots of benefits to the earth’s atmosphere for example:

·         It gives us oxygen for us to breath

·         It absorbs ultra violet light from the sun this UV radiation can cause skin cancer and age skin.

·         The atmosphere also absorbs X-rays and gamma rays and regulates the temperature of the earth thus protecting us from extremes in temperature this is a good thing because it allows water to remain in its liquid form instead of being a gas or ice.

·         The atmosphere protects us from meteoroids by burning them up before they hit the earth this happens by the gases surrounding the meteoroids being compressed this compression creates large amounts of heat and makes the meteoroids burn up.

Although there are lots of benefits to the earth’s atmosphere there are also some drawbacks to it for astronomers for example:

·         Light is refracted and causes stars to twinkle and the clarity of images of the night sky to be effected.

·         The sky is made blue by gas light being scattered through gas molecules

·         The atmosphere is very good at absorbing UV light, gamma rays and X- rays this means that most observatories that require these things to be put on top of big hills where less of their rays will have been absorbed.

The Earth’s atmosphere successfully absorbs most electromagnetic waves but some can successfully pass further than others this picture explains that. The wavelength of the waves can affect how far they can pass and what they are reflected by.

·         The longest waves are reflected back by electrons

·         Slightly shorter wavelengths are absorbed by water vapour and oxygen

·         Infrared radiation is absorbed by water vapour, methane and carbon dioxide

·         Ultraviolet radiation is absorbed by ozone and oxygen

·         X-rays and Gama rays are absorbed by oxygen and nitrogen