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First Oort Cloud Object May Have Been Discovered
SpuriousLogic alerts us to the discovery of what may be the first object ever discovered from the inner edge of the Oort cloud. 2006 SQ372 was found on images from the Sloan Digital Sky Survey. Its discoverers theorize that this comet-like object and the planetoid Sedna, first spotted in 2003, might be Oort denizens. Sedna is in a stable orbit but 2006 SQ372 has been perturbed by the gravity of Uranus and/or Neptune, simulations suggest, so its orbital history is unknowable. 2006 SQ372 will travel out to 1,600 AU on this orbit, making it the most distant solar-system object yet found. The Oort cloud is believed to extend ten times that far, or about a quarter of a light-year. "Theoretical models of the formation of the Oort Cloud predict that it should also host a massive inner part, but comets from this region never make it near Earth. To see the long-period comets from the inner region of the Oort Cloud requires observing comets whose orbits always stay well outside Saturn's orbit — like 2006 SQ372."
Something tells me that a lot of people are going to be looking up Oort Cloud on Wikipedia in the next few minutes... the article summary is nice and scientificky but it hardly explains what's going on in simple terms - the article is actually more summarised than the summary!
For reference, see the article itself or:
http://en.wikipedia.org/wiki/Oort_cloud
From the Wikipedia article:
The outer Oort cloud [...]. Its total mass is not known with certainty, but, assuming that Halley's comet is a suitable prototype for all comets within the outer Oort cloud, the estimated combined mass is 3x10^28 grams, or roughly five times the mass of the Earth. Earlier it was thought to be more massive (up to 380 Earth masses), but improved knowledge of the size distribution of long-period comets has led to much lower estimates. The mass of the inner Oort cloud is not currently known.
It seems that Sedna is sometimes regarded as an inner Oort Cloud object. But this seems to be disputed since it's a lot closer than the supposed location of the Oort Cloud but much farther away than the Kuiper Belt objects.
Does this
Incorrect, the sum of the mass of the Oort cloud objects *might* be larger than the Earth's mass, maybe even a few Earth masses, but it is certainly not "far more than the mass of the sun and all the planets".
While an Earth sized planet might exist in the Oort cloud and not be detected, it is essentially impossible for anything Jupiter-sized to exist there, for two reasons: (a) Infrared all-sky surveys would have detected it by now and (b) a massive object like that would cause a significant detectable influx of smaller objects (comets) from the region where it exists. No such "preferred" direction is detected in long-period comets, and the number of long-period comets we find is at least an order of magnitude lower than we would see if there really was such a massive object out there.
Yes, this is the "Nemesis" theory, which was popular in the '70s and '80s for explaining "regular" extinction events. However, the events are less "regular" than suggested by proponents of the theory, and if such a star really existed, Infrared All Sky Surveys would have detected it by now. They haven't, so it doesn't exist.
Yes, there was a serious theory for a while that a small dim star called "Nemesis" orbits the Sun and would disrupt the Oort could every 40 million years or so sending a hail of comets into the inner solar system which is responsible for mass extinctions on Earth. It never really had many supporters.
I addition to Nemesis, which at least was a theory espoused by legitimate astronomers, many kooks are convinced that there is a weird giant planet out in that same area which swings by Earth every few thousand years and is supposedly the home to a race of lizard people who communicated with the Sumerians. Now go to bed or the lizard people will get you.
Does this
A dwarf planet and a plutoid are not mutually exclusive. A plutoid is a subset of dwarf planets that are further from the Sun than Neptune. Sedna has not yet been designated a dwarf planet or a plutoid because there is currently a debate in the IAU about the characteristics of a body for its self gravity to round it. Sedna is currently classified as a planetoid (or minor planet). However, Sedna is considered a strong candidate to become both a dwarf planet and a plutoid since a) its estimated diameter of ~1500 km is larger than the 800 km that is expected to round a rocky dwarf planet, and b) it is likely made of a significant fraction of ice which would significantly lower the diameter needed to round it. I don't expect the debate in the IAU to be resolved anytime soon, but I think Sedna will be reclassified because its characteristics overwhelmingly support the likelihood that it has enough gravity to round itself.
"I'm willing to go as far as to say it was one of these objects that was responsible for the destruction of a now ghost planet between Mars and Jupiter."
No, that was the Martians.
I reserve the write to mangle english.
Just to make you paranoid, the sum of the mass of oort cloud objects is far more than the mass of the sun and all the planets
Not supposed to be. The mass in the Oort cloud can be estimated by assuming some sort of mass function (i.e., a distributon of number, and thus total mass, with the mass of the object. Unless there a some unknown big objects out there, the total mass is order one Earth mass to maybe 100 Earth masses. And, there have been negative searches in the IR for very large (Jupiter size and larger) objects, so it's almost certainly nowhere near as large as 1 solar mass.
It is interesting that the "knots" seen in the Helix Nebulae are likely to be super-comets (Sedna sized bodies ablating under the bright glare of the dying central star), so if you want to get a look at an Oort cloud, here is a good one.
You missed this in the Wikipedia article:
I thought the latest theory was that Oort cloud disruption occurred as our sun fluctuated up and down through our arm of the galaxy, as we circle around the core?
I drank what? -- Socrates
Composition? We can tell where various meteorites came from by their composition -- we know when a particular rock originated from the asteroid belt or was blasted off the surface of the moon or Mars by looking at the composition. Since we haven't done it yet we certainly don't know, but it's quite possible that it would be equally obvious whether a comet originated from our own cloud or some other star's, based on its composition, assuming each star has its own, detectably different balance of elements. This probably wouldn't be true of first generation stars, but second or third generation stars like our Sun will have an overall solar system composition that is dependent upon the exact size and nature of the star whose supernova explosion created the elements that later came together to form it and its surrounding planets. This may be easily detectable. Of course, we'll have to get our hands on some extra-solar comets to be sure. If it isn't, we'll just never know if we have or not, but if it is, it should be quickly obvious once we do.
"Convictions are more dangerous enemies of truth than lies."