[meteorite-list] Mercury data
From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Sun, 19 Jun 2011 22:45:21 -0500 Message-ID: <E6124FB858DC42B3902BFA58C4FCEC1F_at_ATARIENGINE2> What they say about it: "As to what to call these newfound objects, Wambsganss favors brevity. "I think the most intuitive name is 'free-floating planets,' but if we decide to adopt that name then we have to give up one of our definitions of a planet," he says. "A free-floating planet is a contradiction, because a planet is by definition bound" in an orbit around a star. That contradiction will no doubt fuel controversy-McCaughrean calls "free-floating planets," a term that appears once in the new study, "a red rag to a bull." Even the more conservative "free-floating planetary-mass objects" can be misleading, McCaughrean says. "To me, that's somewhat still equivalent to calling a Chihuahua a 'cat-massed object,'" he says." http://www.scientificamerican.com/article.cfm?id=free-floating-planets-microlensing Please, somebody give their Chihuahua the name CMO... "What is more, no stars were observed within 10 astronomical units of the lensing objects - one astronomical unit is the distance between the Sun and the Earth and Saturn orbits at about 9 astronomical units. " http://physicsworld.com/cws/article/news/46022 Why assume they have no stars? Saturn is at 9.585 AU, BTW, not 9 AU. Couldn't we have a Jupiter at Uranus distance (20 AU)? Just because we have trouble finding Jupiters at 10 AU in distant solar systems doesn't mean they aren't there. The gravitational tug-and-wobble of a Jupiter at 10 AU is small indeed. Have we got one? http://www.popularmechanics.com/science/space/deep/our-galaxy-is-littered-with-orphan-planets-5766646 A TRILLION free planets in our Galaxy? http://www.skyandtelescope.com/news/home/122278839.html How micro-lensing works (an animation): http://planetquest.jpl.nasa.gov/news/freePlanetAnim.cfm We should remember that the "orphan planets" cannot be seen by the telescope, only be detected by their micro-lensing "flash" and if they do have stars close to them those stars would be too faint to be seen with any telescope now in operation. "I have seen the dark universe yawning Where the black planets roll without aim; Where they roll in their horror unheeded, Without knowledge or lustre or name." -H. P. Lovecraft, Nemesis, 1918 Sterling K. Webb --------------------------------------------------------------------------------------------- ----- Original Message ----- From: "Pete Pete" <rsvp321 at hotmail.com> To: <sterling_k_webb at sbcglobal.net>; <agee at unm.edu>; "meteoritelist meteoritelist" <meteorite-list at meteoritecentral.com> Sent: Sunday, June 19, 2011 9:28 PM Subject: RE: [meteorite-list] Mercury data Hi, Sterling and All, Here's an interesting little article I came across in Nature: http://www.nature.com/nature/journal/v473/n7347/full/nature10092.html http://www.nature.com/nature/journal/v473/n7347/full/nature10092.html "Unbound or distant planetary mass population detected by gravitational microlensing" I know they've suspected wandering stars in the past, but now planets! If there's these big ones, what's to say there aren't smaller ones? Best, Pete ---------------------------------------- > From: sterling_k_webb at sbcglobal.net > To: agee at unm.edu; meteorite-list at meteoritecentral.com > Date: Sun, 19 Jun 2011 17:59:52 -0500 > Subject: Re: [meteorite-list] Mercury data > > Thanks, Carl. That's was what I was hoping for. > > There are two "Theories of Mercury" --- the old one, > that Mercury formed from inner disk materials, all > iron and refractories, and the new one, that Mercury > suffered a "Giant Impact' which added its iron to the > Mercurian core but blasted Mercury's crust off to be > lost. > > Sometimes the Giant Impact Theory is interpreted > as a much-larger Mercury that lost much of its crust > to a series of Pretty Dam Big Impacts that contributed > no iron but blasted Mercury's crust off to be lost just > the same. > > The old "All Iron And Refractories" theory seems, at > first glance, to be dead, but wait! there's still a heart > beat. The Crust is not The Planet. If Mercury has been > pasted through the ages by errant asteroids and comets > from Out-System that have been tossed down into high > eccentricity orbits, that crust of volatiles could be the > accretion of 4 billion years of Jupiter's trash toss-out. > > There's a lot wrong with this idea. It's hard to deliver > material to Mercury without splashing it right off into > the grip of the Sun's powerful gravity, and it would > take a lot of material to pave a planet miles deep. > Perhaps the "anomalous" crust was delivered by the > Late Bombardment? > > Sulfur, visible as yellow swirls, streaks and patches > surrounding the pits that burped it, got up and > screamed "Volatiles!" even before those scans were > released. It's just like Io, but a lot hotter. It can't > accumulate like it does on Io Still, if Mercury is > still boiling out sulfur after "billions and billions" > of years, it must have started with a LOT of volatiles. > > Recent images of Mercury can be found at: > http://www.nasa.gov/mission_pages/messenger/multimedia/mercury_images_coll_archive_1.html > > > Maybe Mercury formed farther from the > > Sun and migrated inwards... > > It's a whole new solar system. Jumpin' Jupiter > wandering back and forth . Now, we have Migrating > Mercury. The problem is "migrated from where?" > Where do huge-iron-cored terrestrial planets with > scads of volatiles form? It's really hard to think of > any spot that provides vast amounts of both. > > > Sterling K. Webb > ------------------------------------------------------------------- > ----- Original Message ----- > From: "Carl Agee" <agee at unm.edu> > To: <meteorite-list at meteoritecentral.com> > Sent: Sunday, June 19, 2011 11:16 AM > Subject: [meteorite-list] Mercury data > > > > Of course it's still early days on understanding the Mercury data > > coming back from Messenger, but I think there are a few simple > > things > > that can be said about the two geochemical graphs that were part of > > the press release. The major element graph of Al/Si versus Mg/Si > > clearly shows that the measured Mercurian surface is similar to > > basaltic and mantle rocks from the Earth. They plot along the Earth > > array and look to be a bit more olivine-rich than mid-ocean ridge > > basalts, but not as olivinerich as mantle peridotites, perhaps more > > like Archean Earth komatiites. The measured Mercurian surface is NOT > > delpleted in aluminum, like Martian basalts or Angrites. Also, > > Messenger is clearly not measuring rocks like the lunar anorthositic > > highlands. The major element that is still missing from this puzzle > > is > > iron. The data do not say anything about the FeO content of the > > Mercurian surface -- this is a pretty big deal, and until that is > > known it will difficult to know exactly what we are looking at -- > > let > > alone if there is a match for any known meteorite type. > > > > The potassium/thorium plot shows that Mercury is a lot like the > > other > > terrestrial planets in terms of volatile element content. It seems > > to > > be closest to the K/Th of Mars which is quite surprising, since Mars > > is thought to be the most volatile rich of the rocky planets. This > > runs counter to the idea that the inner solar system is chemically > > zoned with volatile elements concentrated out at Mars and lower in > > towards the Sun. But who knows? Maybe Mercury formed farther from > > the > > Sun and migrated inwards. > > > > There was a brief mention of substantial amounts of sulfur, but no > > data in the multimedia press release, so it would be interesting to > > know what they mean by "substantial amounts". Also, why do they > > think > > it is in the form of sulfide and not sulfate? > > > > See how important these missions of planetary exploration are and > > how > > fragmentary our understanding is? > > > > Just my opinion.... > > > > Carl Agee > > > > -- > > Carl B. Agee > > Director and Curator, Institute of Meteoritics > > Professor, Earth and Planetary Sciences > > MSC03 2050 > > University of New Mexico > > Albuquerque NM 87131-1126 > > > > Tel: (505) 750-7172 > > Fax: (505) 277-3577 > > Email: agee at unm.edu > > http://epswww.unm.edu/iom/pers/agee.html > > ______________________________________________ > > Visit the Archives at > > http://www.meteoritecentral.com/mailing-list-archives.html > > Meteorite-list mailing list > > Meteorite-list at meteoritecentral.com > > http://six.pairlist.net/mailman/listinfo/meteorite-list > > ______________________________________________ > Visit the Archives at > http://www.meteoritecentral.com/mailing-list-archives.html > Meteorite-list mailing list > Meteorite-list at meteoritecentral.com > http://six.pairlist.net/mailman/listinfo/meteorite-list = Received on Sun 19 Jun 2011 11:45:21 PM PDT |
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