Phobos, Deimos and Gaspra comparison

[vogon13]

Post deleted by vogon13<br /><br />{messed up the width, and fixed it in the next post}<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[vogon13]

Found this intersting picture at the JPL website.<br /><br />Interesting to have a side by side comparison.<br /><br />Phobos (the 'fat one on the right) and Deimos (the bean) are moons of Mars, and Gaspra (the pointy one, is an asteroid. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[vogon13]

{heh, heh, despite my lack of computer skills, I seem to be unique in having an ability at fixing width screw-ups!}<br /><br /><br /><img src="/images/icons/laugh.gif" /><br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[michaelmozina]

That pretty cool having them side by side like that. <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[JonClarke]

Very nice indeed! <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[brandbll]

I wouldn't even consider those things moons. Just stuck asteroids. <div class="Discussion_UserSignature"> <p><font size="3">You wanna talk some jive? I'll talk some jive. I'll talk some jive like you've never heard!</font></p> </div>

 

[JonClarke]

It's a matter of definition. If it orbits a planet, it's a moon, if it is in an independent orbit round the sun it's an asteroid (or planet, if big enough).<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[robnissen]

True enough. But no one has ever come up with a good lower limit for a moon. If there isn't one, Saturn has billions of moons, and all the other ringed planets probably have millions of moons. That seems absurd. I would think a moon should have a minimum size. Maybe 10 km. along its longest axis?

 

[qso1]

I did mental comparisons years ago, probably around the time of the Gaspra flyby. I, like many others suspected Mars moons to be captured roids and the generally similar appearence of Gaspra seems to reinforce the theory. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[mikeemmert]

Thanks for the photos, vogon.<blockquote><font class="small">In reply to:</font><hr /><p>I, like many others suspected Mars moons to be captured roids and the generally similar appearence of Gaspra seems to reinforce the theory.<p><hr /></p></p></blockquote>I don't find the appearance of these ojbects so similar. The moons are considerably more rounded than the asteroid, and the surfaces seem to be much dustier.<br /><br />I advance no explanation at this time.

 

[tom_hobbes]

That has more to do with the quality of the photograph I think. <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[JonClarke]

Why shouldn't Saturn have billions of moons? For ease of use it might be useful to have a category of "minor satellite bodies" for bodies than that, say, 1 km. It this would be arbitary only. There are no laws of nature that say that only satellite slarger than a fixed distance count.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>I did mental comparisons years ago, probably around the time of the Gaspra flyby. I, like many others suspected Mars moons to be captured roids and the generally similar appearence of Gaspra seems to reinforce the theory.<p><hr /></p></p></blockquote><br /><br />Not to burst your bubble or anything, but that's been a popular explanation for them for many years. Phobos in particular orbits too close to Mars for it to have always been a Martian satellite; its orbit is unstable. Therefore it had to have been captured gravitationally, and therefore it was once an asteroid. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[robnissen]

"Why shouldn't Saturn have billions of moons?"<br /><br />Perhaps, but I'm not sure a classification that puts the Moon, Titan, Europa, etc. into the same category as specks of dust orbiting in Saturn's (or another planet's) rings, is a terribly useful classification. That being said, I'm not sure we have a major disagreement, I proposed a 10K lower limit for a moon, you proposed a 1k lower limit. You are right, any limit is arbitrary, but on the other hand, without a limit, we are left with not knowing how many moons any planet has. I assume that it is possible that the earth has captured bits of dust that now circle the earth. Are those bits of dust moons, and if so how many moons does the earth have. I think most would agree that microscopic dust that orbits a planet is not a moon, thus we already have an arbitrary limit, we are just lacking a number. Whether the arbitrary limit is put at 1K, 10K, or some other number, I don't really care, as long as dust, pebbles and ice chips are not counted as moons.

 

[qso1]

They appear pretty similar to me but having said that. I stated that I suspect they may be captured asteroids, not that they are without doubt captured asteroids. Also, by similar, look at the asteroid depicted in "Armageddon" which looks very little like Gaspra. This was of course because Gaspra is not dramatic enough for the "Die Hard' of space. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

Calliarcale:<br />Not to burst your bubble or anything, but that's been a populal...<br /><br />Me:<br />My bubbles still intact LOL. I mentioned "I, like many others..." The many others included scientists who for many years theorized the probability of Mars moons being captured asteroids.<br /><br />My mental comparison is just a way to see if the captured asteroid theory had any teeth. IMO, it did.<br /><br />Belive me, I'm not smart enough to come up with original new theories on my own nor dumb enough to try to claim others are mine. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

If you were to compare Phobos to Tethys, I could see where there is very little similarity but IMO anyway, there is enough similarity between the compared examples here to reinforce the idea that Phobos and Deimos are captured asteroids.<br /><br />They could be captured comets but that seems unlikely because they are close enough to the sun to produce a comet tail.<br /><br />Bottom line, unless we go to Phobos, Deimos, and an asteroid. We won't really know. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>