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Previous Next Up Topic Cosmology / Alternative Cosmology / Venus & Mars (5717 hits)
By Mike Petersen Date 2008-12-31 23:01
First, Happy New Year to all...

It has been postulated that Mars has no atmosphere because it lost its magnetic field billions of years ago.  This might be because of a cataclysmic collision (again postulated) that caused the vast geological differences between the northern and southern hemispheres of the planet.  It may also be because Mars cooled off faster because of its size, thereby losing its molten core and dynamo effect.  And, with no atmosphere, it was not able to sustain liquid water, although the Phoenix lander has definitely proven there is water ice on Mars, and more than likely it had much more water before it lost its atmosphere.

Well, okay, I can buy all that.  But now we come to Venus, the hothouse of the Solar System.  It also has no magnetic field, but it definitely does have an atmosphere.  It also rotates on its axis in the opposite direction from most of the other planets.  My conjecture is that it was also smacked by another large planetoid early in the Solar System's development.  This collision happened in such a way as to cause the planet to either start rotating the other way, or cause it to wobble on its axis so much that it eventually turned over 180 degrees, thus causing the apparent reversal of spin.

So, no magnetic field.  Then why did it keep its atmosphere?  I believe it's because of volcanic activity still going on within the planet that is spewing out gases, enough to keep its atmosphere.  I think there may be two reasons for this inner activity.  First, its proximity to the Sun.  It's closer, so gets more heat, so cools off more slowly.  Second, the collision I talked about above.  It could have kabonged Venus so hard that it still has inner activity keeping it warmer.  Venus also may still have a molten core, but it may not be spinning, so no dynamo effect.  This again could have been caused by my hypothetical collision.  The whack that caused it to rotate in the opposite direction may have had a deteriorating effect on the spin of the molten core.

Okay, that's my theory about Venus and Mars.  Start off the new year right by knocking holes in it!

Regards, Mike Petersen
By lyndonashmore Date 2009-01-01 13:35
Happy New Year to one and all.
Just wondering what has the magnetic field got to do with keeping ones atmosphere about one?
Not wanting to change the subject but I have also often wondered why our atmosphere has so little hydrogen in it if it is the building block of the universe.
By Mike Petersen Date 2009-01-02 14:14
Lyndon wrote:

what has the magnetic field got to do with keeping ones atmosphere

If a planet has no magnetic field, then the solar wind is not deflected and proceeds directly to the planet, slowly but surely shredding the atmosphere and blowing it off into space.

By lyndonashmore Date 2009-01-02 20:19
In that case we should be able to develop a relation between the 'height ' of the atmosphere and the strength of the planets magnetic field. i understood that it was to do with temperature.
By Jade Annand Date 2009-01-02 21:15
Here's an older article on the subject:

The article said:

...That's a puzzle to planetary scientists, because Mars's surface is littered with signs of liquid water. Dried up valley networks, sedimentary deposits, and chaotic flood plains hint that billions of years ago Martian water flowed freely and that the atmosphere there must have been substantially thicker than it is now. But where did it all that Martian air go?

New evidence from NASA's Mars Global Surveyor (MGS) spacecraft supports a long-held suspicion that much of the Red Planet's atmosphere was simply blown away -- by the solar wind.

An even older article from 2000 goes into a little detail about Mars' current magnetic patterns and ionosphere.

As for Venus, it seems to be a bit of a weird situation, since even though it has no planet-induced magnetic field, it does have an induced magnetosphere.
By Jade Annand Date 2009-01-04 08:38
Oh yes, and HAPPY NEW YEAR!
By Mike Petersen Date 2009-01-05 14:53 Edited 2009-01-05 15:54
How about that!  There's a new article out that substantiates my statement about the atmospheres of Venus and Mars.

Where Venus' Water Went

Here is the relevant quote:

The solar wind carries electrical and magnetic fields throughout the solar system and "blows" past the planets. Earth's magnetic field protects us from the charged stream. But Venus doesn't generate a magnetic field. There, the solar wind strikes the planet's upper atmosphere and carries particles off into space.

You can substitute "Mars" for "Venus" and we have both planets covered.

Regards, Mike
By Ari Jokimäki Date 2009-01-05 19:09
So, with good reason we can now say that "you heard it here first"! :)
By Mike Petersen Date 2009-05-07 13:35 Edited 2009-05-07 13:38
And another vindicating article:

Was Mars Magnetic Field Blasted Away?

Hmm...I hit this one on the head...I wonder if, in a previous life, I was a Marsupial?


- Mike Petersen

PS - Oh, and Lyndon, I think the reason you don't find Hydrogen in our atmosphere is because it's all caught up in that pesky Dihydroden Oxide permeating our planet.
Previous Next Up Topic Cosmology / Alternative Cosmology / Venus & Mars (5717 hits)

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