Archive for November, 2017

Giving Thanks for Our Miraculous Home–the Earth

Monday, November 20th, 2017

     How often do we think to be grateful for this earth?  At Thanksgiving time, we know to look around the table and give thanks for the people we love and the food we share.  And other cherished gifts like freedom and health.

     But we really ought not to take for granted this small planet whose very special properties have made possible this system of life of which we are a part.  Scientists have called Earth ‘the Goldilocks planet,’ just right for life.  If certain aspects of our planet were just a little bit different, life on Earth would be impossible.

     Several factors make Earth ‘just right’ for life:

Earth’s location in the ‘Goldilocks zone’

     The distance between Earth and the sun is just right.  If we were a little nearer the sun, like Venus, our planet could be a cloudy furnace.  And if we were a little farther from the sun, like Mars, Earth could be a cold desert.  

     Our Goldilocks position in relation to the sun means that Earth’s temperatures are just right for water to persist  in liquid form.  And liquid water has been essential to the development of life.  Water is capable of dissolving many substances, and the ingredients for life as we know it–proteins, DNA, etc., can move around in water and interact with each other. 

The sun’s ideal nature

     Our lives would be impossible were it not for the sun’s great longevity and stability.

     While many stars live for only a few million years, our sun is already well over four billion years old.  And scientists believe it is only about half-way through its life-span.  If our sun were a short-lived star, life on earth would not have had time to evolve to the point that it has.  For example, the oldest known organisms appeared on Earth 3.5 billion years ago.  And more complex life took much longer to evolve, with the first multi-celled animals appearing only some 600 million years ago.  The sun’s longevity has enabled the long process of evolution,  resulting in higher orders of life on Earth, like humans.

     And unlike many volatile stars, our sun is stable, with relatively little variation in its emission of radiation.  However, if the earth were in the orbit of an unstable star that emitted violent bursts of radiation, life could have been scoured from our planet long ago. 

The earth’s magnetic field

     Another essential ingredient in Earth’s hospitality to life is its magnetic field.  The earth’s molten metallic core creates a protective field, which emanates from the poles and encircles the planet.   Without this magnetic field, we would all be fried by cosmic rays and solar storms. 

Plate tectonics and the moon 

      Plate tectonics and the moon have also played important roles in the existence of life on Earth.

     The shell of the earth is broken into constantly moving plates.  And surface rocks, which have absorbed carbon dioxide from the atmosphere, are dragged downward, where they melt.  The molten rock eventually releases this carbon dioxide gas back into the atmosphere through volcanic activity.  Without this process, the atmosphere’s carbon dioxide would continue to be absorbed by rock until the planet would eventually freeze.

    And the earth’s tidal regions, where the moon’s gravitational tug (aided by the sun), has caused the regular ebb and flow of tides, may have been just right environment for life to begin.

So Are We Alone in the Universe?

      Clearly, an incredible combination of circumstances aligned perfectly for our planet to host life so abundantly.  Are there other planets that also host life?  Given the mind-boggling number of planets that exist in the universe, scientists have long thought that even if an infinitesimal proportion of them hosted life, there would still be other planets out there where life exists.

     But recent research that has caught the attention of the scientific community questions whether there are, in fact, any other planets anywhere, where life exists.   Astrophysicist Erik Zachrisson. at Uppsala University in Sweden, used recently available computer modeling to determine that out of 700 quintillion (that’s a seven followed by 20 zeroes!) planets in the universe, Earth is unique.  In fact, says Zachrisson, statistically speaking, even one planet like ours should not exist!

     The jury is still out.  We do not know if Earth is the only planet in the vast universe that hosts life.  But we do know that a planet like ours is not the ‘norm,’ that at the very least is very uncommon.

     And I am very thankful for all the circumstances that aligned to make Earth a planet that is filled with life, including mine and the lives of all those I love.–April Moore 


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