Astronomy

Astronomy coursework

Earth atmosphere

There are three types of Earth atmosphere are known today and they can be distinguished by their chemical composition . The present atmosphere is usually referred to as the 3rd atmosphere , as it appears to be the latest

The first type of atmosphere was primarily composed of helium and hydrogen , and the heat provided by the sun and still-molten crust dissipated the atmosphere

The second atmosphere was formed about three and a half billion years ago after the surface had cooled enough to form a crust and

the Earth was filled with volcanoes releasing steam , ammonia and carbon dioxide Thus , the second atmosphere was primarily composed of water vapor carbon dioxide , and some nitrogen but no oxygen . The second atmosphere had about 100 times as much gas as the current atmosphere . It is generally believed that the greenhouse effect , caused by high levels of carbon dioxide , kept the Earth from freezing

The present atmosphere has an oxygen-nitrogen composition , which is enforced by oceanic blue-green algae , while the carbon dioxide levels significantly dropped . Oxygen does not remain naturally free in an atmosphere , but tends to be consumed (by inorganic chemical reactions animals , bacteria , and land plants at night , while carbon dioxide tends to be produced . Although carbon dioxide dissolves easily in water , while O2 tends to be expelled by it . There is a balancing amount of oxygen and carbon dioxide that keeps the algae moderately active . The excess of carbon dioxide makes the algae more active and vice versa

Craters and yong rocks

On Earth , impact craters are harder to recognize because of weathering and erosion of its surface . Approximately 80 of Earth 's surface is less than 200 million years old . The surface that is witnessed presently on Earth was formed only in latest stages of the earth development . That explains the relatively young age of rocks and small amount of recognizable craters

Magnetic field

Magnetic fields are usually produced by the motion of electrical charges . There is no clear explanation how the Earth 's magnetic field was originated , but it is theoretically believed that it depends on the production of electrical currents by the coupling of convective effects and rotation in the spinning liquid metallic outer core of iron and nickel . This process is usually referred to as dynamo effect

Venus

The two of the planet 's most predominant features are crystal plateaus and volcanic rises , which were formed by a mechanism similar to hot spot plumes , a process still active on Earth today and evident in the Hawaiian Islands . Hotspots are thermal plumes of hot rock originating deep within the Earth and rising buoyantly upward over millions of years

Mars

There is water presently on Mars . There is evidence of of water frost on the surface . The frost is known to be water frost because the temperature was too high for carbon dioxide frost . However , there is no liquid water on Mars . Water is only present on Mars in the form of ice or water...