Earth is the third planet in our solar system. It's size, mass, distance from the sun, and elemental make up is the foundation that created the life on it. If any one of these parameters was different, the life could have been very different or indeed their might have been no life.
The size and mass of Earth has a direct relationship to the shape and size of the creatures and plants spread over its surface. High gravity would have meant that any living entities would have been shorter and probably more sturdy. Lighter gravity would have probably led to more delicate and intricate life forms that would not be able to withstand as much barrage from everday occurances.
The distance from the Sun dictates the weather, the temperature, and the time it takes for a planet to rotate once. If the Earth was substantially closer, then the temperature of Earth would also be substantially hotter. By looking at the deserts it is resonable to make such a hypothesis that the earth would have been far more barren, with fewer life forms that are more specifically designed to retain water. This might have ruled out animals ever existing on the planets land mass.
If the Earth was further away from the Sun, the temperature would be reduced with more chance of freezing temperatures all year through. This would mean that any life that exists would more than likely be sea dwelling only, and probably would live closer to the sea bed where the water would not turn into ice because of the high pressures that are created by the weight of the above water layers.
The elements on the planet have dictated that the life forms are carbon based, from the smallest microbes to the largest lifeforms. If their had been no carbon, would their have been an alternative element to form the main building block. It is unknown at this time, as no other element has been found which makes up the majority of any living entity.
Earth's life forms are indeed very diverse, with enitities such as viruses as small as 20-300 nm, to trees that are 60 metres or taller. It would appear from the evidence on Earth that once life starts to grow, it can develop to withstand major differences in climate, pressure, and indeed other life forms. In total their are many millions of different life forms with more being discovered all the time. When there are so many different species it takes relatively less time for new species to be created. At the beginning of life it is thought that the first lifeforms of bacteria (prokaryote) existed for over 2 billion years before developing into the next stage (eukaryote) fungi, plants and animals.
The surface of Earth is made up of large plates that are constantly moving, against each other. The interaction between these plates (tectonic activity) is responsible for creating volcanoes and earthquakes that occur all over the planet. About 2 billion years ago, all the plates that form the land masses were part of one large continent that started to break up and drift in several directions. By looking at the outlines of the continents and islands it is possible to see which land masses were joined and where. For instance if England was tilted clockwise by about 70 degrees and then moved downward it can be seen that it was joined to the European landmass stretching from the middle of the French coast up to the German Coast. Another example is South America which can be seen on the right coast from the south of Argentina up to Suriname that it almost matches the west coast of the African nations from South Africa up to around Guinea
The Moon
The surface of the Moon is like a photograph in time, enabling us to see the cataclysmic events that occured during the early life of the solar system. All the millions of craters that have occured on the surface have been kept in almost perfect condition as there is no atmosphere and no recent volcanic activity with which to destroy them. There have been volcanoes in the past which is evident by the maria (lava beds) that can be seen. Although it is thought the last volcano happened 100's of millions of years ago.
The craters vary greatly in size from about 1mm in diameter to the largest which is approximately 1600km wide. Because the Moon and Mercury are similar in appearance and at different areas in the solar system, it is possible to deduce that these sorts of craters and collisions would have probably occured throughout the solar system, even on Earth.
Planetary Information
| Maximum Distance from the Sun | 152Mkms |
| Minimum Distance from the Sun | 147Mkms |
| Diameter | 6974km |
| Mass | 1 |
| Sidereal period | 687d |
| Rotation period | 24h 37m |
| Velocity | 47.9km/s |
| Gravity | 1 |
| Maximum Temperature | 60 C |
| Minimum Temperature | -40 C |
| Number of Moons | 1 |
| Escape Velocity | 40300 km/h |