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Year : 2019  |  Volume : 67  |  Issue : 8  |  Page : 204-

Opportune circumstances for sustenance of life on a planet


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. Opportune circumstances for sustenance of life on a planet.Neurol India 2019;67:204-204

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. Opportune circumstances for sustenance of life on a planet. Neurol India [serial online] 2019 [cited 2022 Jun 28 ];67:204-204
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This picture has been contributed by Dr. Manmohan Singh, Professor, Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi.

The sun provides us our life-sustaining energy. It is the centre of the solar system. Although it appears stationary, it moves along its orbit at an average velocity of 450,000 miles an hour. The sun was formed more than 4.5 billion years ago. To sustain life in the form that we recognise, a habitable planet has to have certain unique ‘earthlike’ features. It should orbit a star that has a stable energy output for billions of years, which in our case, is the sun. It should be in the “Goldilocks” zone so that it is at an optimum distance from the source of energy to maintain a suitable life-sustaining temperature. This will ensure that its surface water is liquid, not frozen. It should have plenty of water to sustain the chemical reactions necessary for life. The distance from the sun and the mass of a planet also determine whether or not it can retain “light gases (or any gases) in its atmosphere. The atmosphere of the earth, that predominantly contains oxygen and nitrogen, is ideal for sustenance of life and is dependent on this ‘ideal’ distance between the sun and the earth. The planet should have a circular orbit around its sun so that constant weather conditions prevail. There should not be a source of high radiation close to it. The presence of a large planet, such as Jupitar, that has an immense gravitational field, close to the planet sustaining life, like the earth, is also essential. The immense gravity of the large planet helps in deflecting most of the comets that enter the solar system away from the planet on which life is thriving. Without this large planet with an immense gravitational field, comets would collide with the planet that is sustaining life forms, much more frequently. In this photograph, taken in Jaisalmer, Rajasthan, the tourists sitting on the camel's back and their guide are completely unaware of how lucky they are to be present at this point in time in the history of the earth where every circumstance is opportune for sustenance of their life. This picture has been taken by a Canon EOS 5D Mark III, Lens 24-105mm, f/4.5-5.6