Tuesday, March 9, 2010

Planets Collided and Life Was Made Possible

How old is the Earth? How did it form? Why does Earth have conditions that support life? Scientists are still pursuing answers, but what they've learned so far is fascinating.

Yesterday, I talked about the chance asteroid impact that caused the extinction of dinosaurs, which made it possible for mammals to flourish and evolve into the human species. Today, I'll talk about another, much grander impact--and the consequences for life on our planet.

A number of factors make it possible for life to flourish on Earth's surface. Two of them have their origins in early Earth history.

One factor is the Earth's electromagnetic field, which is strong enough to extend well into the upper atmosphere. It deflects radiation from the sun and cosmic rays from faraway events in the universe. Without the protection of this field, these deadly particles would reach the surface unfiltered, killing living organisms and stripping away most of the atmosphere. The result would be a planet like Mars, which has no magnetic field, no life and practically no atmosphere.

Not all planets have an electromagnetic field. Earth is unique and fortunate to have a large, molten iron core which is constantly in motion. It is this churning of molten iron that creates the electromagnetic field.

Another factor is that even though the Earth rotates on a tilted axis, it does not wobble. The reason the Earth's axis is so stable is that the moon's size and closeness creates sufficient gravitational pull to hold it in place. The consequence is that climates on Earth are relatively stable. If our moon wasn't as big as it and as close as it is, the Earth's axis would wobble back and forth widely, causing abruptly changing climates, conditions so chaotic that life as we kinow it could not exist.

So why are we so lucky? The answer has to do with with how our moon was formed.

4.5 billion years ago, as the matter left over from the formation of our sun was slowly coming together to form planets, the Earth's surface was a hot radioactive sea of molten rock. Meteors and comets rained onto the surface day and night.

About that time, another of the forming planets, somewhat smaller than the earth, traveled in its elliptical orbit and chanced to collide with the Earth. The glancing blow was catastrophic. The core of this planet merged with Earth's core and an enormous amount of debris was blown into space. As this debris orbited around the Earth, it soon gathered to form our moon.

Earth's enlarged iron core eventually caused our electromagnetic field. And the presence of our large moon stabilized the rotation of the Earth on its axis.

Put another way, this chance glancing blow 4.5 billion years ago--a direct hit might have had quite different, more disastrous consequences--caused our protective electromagnetic field and stable climates.

Put still another way, the chance conditions to support intelligent life in the universe may be more rare than previously thought. Actions have consequences. If this rogue planetoid had missed and continued on its way, you and I would not be here today to talk about it.

[Image copyright byartist James Garry, Fastlight Artwork. Used with permission.]

Post by Dennis E. Coates, Ph.D., , Copyright 2010. Building Personal Strength .


Sean said...

Then again, these collisions might be more common people think. After all, a 2-body problem has a stable elliptical solution; a 3-body problem has an unstable one, leading to one on the bodies to eventually swing out at a great distance and remove themselves from the equation as they get affected by other forces in the neighborhood.

Also, the necessary conditions for life are simply replication and irritability; it's quite possible life occurs in a plethora of situations that people haven't considered. There may be billions of civilizations out there.

Not that it matters. In order for an artificial signal to be detected against the background noise of space, it has to be at the astronomical level. And while it's one thing to imagine life growing out there, it's hard to believe they can create signals as powerful as the sun. Which is probably why SETI never detects anything, despite the billions spent on its wasted efforts.

Finally, even if there was life detected, the laws of physics prevent us from traveling faster than light, which traps us inside a very tiny neighborhood of stars. So we'll never travel to other worlds and meet aliens.

Heck, at the rate our space program is going, it will be decades before we even catch up to what our grandparents accomplished in the 1960's. Sometimes I think technology is moving backwards.

Anyway the upshot of all this is that alien life makes for great science fiction, but if you want to explore new worlds, just walk down the street and introduce yourself to your neighbors.

Anonymous said...

Read the English translation of the Qur'an to understand fully about the creation of the universe and it's creator.

Anonymous said...

And please try to read the books written by Harun Yahya. Wished to give more knowledge to your intelligence so that you would be able to know more of this world and the reason of our creation. Thank you.