Earth-like Planets, Life or Lifeless?
For centuries man has looked at the sky, and wondered, is someone looking back? Science is now closer than ever to answering this quest that is nearly as old as mankind itself. In the last century new technologies and scientific break-throughs have showed us that planets do exist in other solar systems and that there is a probability for other earth-like planets. We have also recognized the parameters and building blocks for life as we know them on earth. But, given these building blocks and parameters, would life actually develop or exist on other worlds?
First, an Earth-like planet is very specific. It must have at least a surface that contains liquid water and an atmosphere. It must also be not only in a planetary system’s habitable zone, but also in a galactic habitable zone. The habitable zone in a planetary system is the zone in the system where liquid water can exist on a planet’s surface and directly proportional to the energy output of the system’s star. For a planetary system to be habitable in a galaxy, it must be far enough away from the galactic center so that radiation levels are low enough for life to develop. Another requirement for Earth-like life to develop on other planets is mass. For example, if an organism from Earth were taken to Jupiter it would be crushed under its own weight due to the high gravity.
The only type of life in the universe as we know it is carbon based life. There is the possibility of life based on other elements, but we have yet to discover it. In order for carbon based life to develop on an Earth-like planet, not only must there be liquid water and the right environmental conditions, but certain elements must also be present. The first and most obvious element that must be present is carbon, another would be nitrogen, oxygen, phosphorus, sulfur, and hydrogen. These six elements account for about 97% of mass in all carbon based life.
In 1961 at University of California,...
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