Mars Eliptical pattern

danish987654 · Apr 28, 2008

I was reading a forum on another website and it said tat mars eliptical pattern might be changing. can any one please explain to me how this can be happening?

bearack · Apr 28, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I was reading a forum on another website and it said tat mars eliptical pattern might be changing. can any one please explain to me how this can be happening? Posted by danish987654</DIV> Maybe since Mars has little to no magnetic field, the solar winds are reforming the planet?  <div class="Discussion_UserSignature"> <img id="06322a8d-f18d-4ab1-8ea7-150275a4cb53" src="http://sitelife.space.com/ver1.0/Content/images/store/6/14/06322a8d-f18d-4ab1-8ea7-150275a4cb53.Large.jpg" alt="blog post photo" /> </div>

MeteorWayne · Apr 28, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I was reading a forum on another website and it said tat mars eliptical pattern might be changing. can any one please explain to me how this can be happening? Posted by danish987654</DIV> The phrase "eliptical (sic) pattern" has no real meaning, so it's kind of hard to figure what they are trying to say.It could mean the elliptical shape of Mars' orbit; all orbits are elliptical, and all change shape and orientation somewhat over time.It could mean ecliptic, which is the path that the sun takes through the sky over the planet's orbit, that would change as the obliquity (angle of the axis of rotation of the planet) changes. All planets change this angle over time. Earth's stays pretty close to 23 1/2 degrees to the plane of the solar system; Mars' changes are more extreme. The large moon we have keeps us more stable.None if this is new, all things things have changed, and will continue to change over the life of the solar system.Can you tell us what website so we can see what they are actually trying to say? <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

DrRocket · Apr 28, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>... all orbits are elliptical, and all change shape and orientation somewhat over time...Posted by MeteorWayne</DIV>Correct me if I am wrong, but I believe that a perfectly elliptic orbit applies to the two-body central force problem with the potential arising from a force obeying the inverse square law.  If the central force varies slightly from the inverse square or if orbits are perturbed by action of a third body I think you may find orbits that are approximately elliptic but that exhibit phenomena like precession, or, in the case of a perturbation from a passing third body, a shift.  If you get significant interactions from several bodies, all bets are off.This may be implied in your post, since if an orbit is perfectly elliptic it cannot change shape and orientation with time.  A truly elliptic orbit is closed.  To change with time you need, in the two-body case, you need a periodic or and  open orbit. <div class="Discussion_UserSignature"> </div>

MeteorWayne · Apr 28, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Correct me if I am wrong, but I believe that a perfectly elliptic orbit applies to the two-body central force problem with the potential arising from a force obeying the inverse square law.  If the central force varies slightly from the inverse square or if orbits are perturbed by action of a third body I think you may find orbits that are approximately elliptic but that exhibit phenomena like precession, or, in the case of a perturbation from a passing third body, a shift.  If you get significant interactions from several bodies, all bets are off.This may be implied in your post, since if an orbit is perfectly elliptic it cannot change shape and orientation with time.  A truly elliptic orbit is closed.  To change with time you need, in the two-body case, you need a periodic or and  open orbit. Posted by DrRocket</DIV> Yeah, I thought the concept of osculating orbits would be a bit much until I found out what was being said.I should have stated "approximately" but didn't want to get too complex too fast <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-foot-in-mouth.gif" border="0" alt="Foot in mouth" title="Foot in mouth" />However, I believe even with a 2 body solution, there is precession (and possibly change in shape) due to the sun's gravity (that pesky Einstein fellow again). IIRC, Mercury's orbit would precess even if it was only the sun and that one planet. It would therefore imply that the same would happen with any other distance, though the effects would be MUCH smaller.In addition, non gravitational forces (Need not be a third body) such as the solar wind, radiation absorbtion/reradiation effects, etc would cause a very small shift in the shape of the ellipse as well.Granted they are very small for a planet sized object, but the forces are not zero.Edited for clarity (6 words) and typos (more than one word) <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

DrRocket · Apr 28, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> ...However, I believe even with a 2 body solution, there is precession (and possibly change in shape) due to the sun's gravity (that pesky Einstein fellow again). IIRC, Mercury's orbit would precess even if it was only the sun and that one planet.Posted by MeteorWayne ...</DIV>Correct.  But when you throw in general relativistic effects the governing force no longer precisely obeys the inverse square law.  That is why I was careful to clearly state that piece of the classical dynamics solution.  In fact, it was the accurate prediction of the precession of the perihelion of Mercury that privided the first real success for general relativity.  Einstein was most pleased, but not at all surprised. <div class="Discussion_UserSignature"> </div>

MeteorWayne · Apr 28, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Posted by DrRocket</DIV> I think we are saying the same thing here.In general terms, an orbit is generally an ellipse (And we don't even know what the OP had in mind, it could be ecliptic, which is a whole different ball o' wax).When you get into the minutae, it's never truely a perfect ellipse. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

DrRocket · Apr 28, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I think we are saying the same thing here.....When you get into the minutae, it's never truely a perfect ellipse. Posted by MeteorWayne</DIV>Yes.I know.  And I know that you know.  I thought the discussion might be interesting and enlightening for the OP.  It might help understand some of the subtleties if he, or others, read the Apophis thread. <div class="Discussion_UserSignature"> </div>

MeteorWayne · Apr 28, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Yes.I know.  And I know that you know.  I thought the discussion might be interesting and enlightening for the OP.  It might help understand some of the subtleties if he, or others, read the Apophis thread. Posted by DrRocket</DIV> Agreed, until we hear back from the OP, all we can do is have a good educational stimulating conversation!!<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-cool.gif" border="0" alt="Cool" title="Cool" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

3488 · Apr 28, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> Yes.I know.  And I know that you know.  I thought the discussion might be interesting and enlightening for the OP.  It might help understand some of the subtleties if he, or others, read the Apophis thread. Posted by DrRocket</DIV>Hi DrRocket, Very true. Like your avatar BTW. Hope the OP clarifies the original point. Replying to: <DIV CLASS='Discussion_PostQuote'>I think we are saying the same thing here.In general terms, an orbit is generally an ellipse (And we don't even know what the OP had in mind, it could be ecliptic, which is a whole different ball o' wax).When you get into the minutae, it's never truely a perfect ellipse. Posted by MeteorWayne</DIV>Hi Wayne,I have some info here, dunno if it was what the OP originally meant???Mars's current axial tilt 23 deg 59', only slightly greater than the Earth's. The axis appears to vary between 14 degrees & 35 degrees. In the remote past, Mars's axis may have varied all the way from being bolt upright 0 degree tilt to being on its side like Uranus & Asteroid 433 Eros, 90+ degrees. The lack of a massive Moon, caused this, though why the varying tilt appears to have moderated, during more recent geological (areological) times is unclear, as the moons Phobos & Deimos are not nearly massive enough to moderate this. There have been suggestions that Jupiter may have moderated this, though that is not proven.Mars's precessional cycle is approx 51,000 years, nearly double the Earth's approx 25,800 year precession cycle & the shape of Mars's orbit varies from a fairly circular eccentricity of 0.004 to a more oval 0.141 every 90,000 years, the current eccentricity is 0.093.Hope the above is of interest?Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

MeteorWayne · Apr 28, 2008

Thanx Andrew, hoped you might have the stats available, I'm busy writing for meteor land and trying to get Rod Stewart tickets for Ann.We must await the rearrival of the danish!!Yummy.<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-tongue-out.gif" border="0" alt="Tongue out" title="Tongue out" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

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