Life on Earth

        The weather is still not cooperating and my star gazing did not happen this week. Instead I am going to talk about one of the reasons that we have life on Earth. There are many factors that make Earth a unique planet in our solar system. One of the things that make Earth unique is the evolution of our atmosphere. This evolution has made life on Earth possible. The very first atmosphere that the Earth had was probably mainly Hydrogen and Helium because that was the gas that was left over in small amounts in the inner solar system.  When oceans appeared the atmosphere would have started to contain water vapor. This is due to the evaporation of the water in the oceans. The Earth was had volcanic eruptions that allowed outgassing. Outgassing is the release of gases that were trapped in rock. The outgassing was able to released carbon dioxide, water, nitrogen, hydrogen, and sulfur dioxide. This would not have allowed life to move out of the water and onto the land. However, there had to be processes that allowed for this to occur or else we would not be here today. In order for life to move to land there had to be oxygen in the atmosphere. There are two processes that allowed for this to occur. One of the processes photosynthesis, this is when planets and certain organism take in sunlight and carbon dioxide and release oxygen. This allows for oxygen to be put into the atmosphere. The second process is when radiation from the sun breaks apart water molecules in the atmosphere. This leaves oxygen and hydrogen separated, the hydrogen will escape into space and the oxygen will build up in the atmosphere. These to processes were able to build up oxygen and life could evolve and also move to the land. The atmosphere also protects the planet from harsh radiation that would have make life on the land impossible.