Slashdot Mirror
Sedna May Have A Moon
ArrayIndexOutOfBound writes "The newly found planet Sedna may have a moon. It appears that most astronomers argue that Sedna is only another proof that neither Sedna nor Pluto are really planets.
Interestingly, the planet has been found by an 'automated sky survey telescope'..."
SYSS Mouse points to a NASA page with more information about "our potential 10th planet. ... It is 130 billion miles away from the sun (900 times Earth's distance from the sun) and has a 10,500 years orbit, compared to Pluto's 230 years around the sun."
Um, the article said it was 13 billion miles out, not 130 billion (now discovering something that size 130 billion miles out would be a real hell of an achievement :)
There's some theorizing that this may be part of the inner Oort shell; I think it more likely that at that distance it's an outer member of the Kuiper bodies.
Given the highly elliptical orbit, it's size, and it's apparently odd surface color, it's also possible that it's a body captured by the sun some hundreds of millions or billions of years ago. Now *that'd* be neat.
SB
It's old. The more humans I meet, the more I like my cats. At least they are honest.
The first link is about an object named "2004 DW". The second link is about Sedna (previous known as 2003 VB12).
The newly found moon is orbiting Sedna, NOT 2004 DW.
The links in the slashdot article are misleading.
According to this page on Sedna, it's got a perihelion (closest approach) of 76 AU, outside of the scattering influence of Neptune. 2000 OO67 has an aphelion like Sedna, but a much closer perihelion at 21 AU.
I thought it was a misprint in the article, so I went to Nature news. Sure enough at perihelion it is 13 billion km from the Sun an at aphelion it is 130 billion km. Wow, usually you only see orbits that eccentric with comets. Which makes it seem more like a captured object rather than one that formed in orbit. Wonder white kind of perturbing influence it has on comets in the Kuiper Belt, admittedly its small and in a very big volume ... still ...
Bitter and proud of it.
Many (non-planet) Asteroids have moons or satellites in orbit about them..
"You lied to me! There is a Swansea!"
I saw one yesterday during Chad Trujillo's colloquium here at CU. Sedna is more or less opposite the Sun from Pluto. Besides, even at 76AU that's more than double the trip for New Horizons. It probably won't make it that far, not to mention the science team still being around.
That would be in english speaking countrys, in countrys where the laguage is latin based, like all latin america The Moon is refered to as 'Luna'
16,777,216 comments ought to be enough for any forum!
Where does everyone keep getting this 10th stuff from... They keep forgetting Quauar and Varuna. Besides, everyone knows there are only 8 planets... :p
Not quite. Even without the presence of other stars to mitigate the Sun's gravitational field, the escape velocity of the Sun two light years away is only about 100 m/s. I don't have exact data on how fast things move out there, but I know that stars often travel past each other at relative velocities on the order of 1 or 10 km/s. I think we can expect most other interstellar bodies to do likewise.
To see a tenfold increase in escape velocity, we need to cut the distance to 0.02 light year. This is about 1250 AU or 1.9e11 km.
In any case, astronomers consider the heliopause to be the edge of the solar system. (Google "voyager heliopause".) This boundary is thought to lie between 90 and 150 AU from the Sun.
Kuiper Belt Objects are about half and half rock and ice, actually. Beyond about 5 AU you expect icey bodies, since hydrogen compounds are way more common than metals and silicates. (The only trouble being that it has to be cool enough for them to condense.)
And, yes, there has long been hypothesized to be (based on dynamical models and, I believe, comet distributions) an Inner and Outer Oort Cloud.
There is some thought that the Inner Oort Cloud should sort of merge with the Edgeworth-Kuiper Belt, although that's mostly speculation.
Since the Edgeworth-Kuiper Belt is thought to stop around 50 AU or so, this object isn't likely to be a KBO. Inner Oort Cloud seems to fit, though.
Most of the Edgeworth-Kuiper objects are hypothesised to be binaries.
... but I will have leave you only with these
This argument raged on in 1998 (I think) when the intnl body of astronomers wanted to classify Pluto as a Trans Neputinian Object with a special number of 1000.
Some other TNO having a moon was used as conclusive argument to relegate Pluto to being a TNO (the most significant TNO, if you will).
I had links to the above
http://www.solstation.com/stars/kuiper.htm
http://www.solstation.com/stars/ekos-01.jpg
Atmospheric (or lens) diffraction, I'd say. If you were out in space, you could probably block it out with the tip of a pin.
More info on this here.
Why would anyone engrave "Elbereth"?
Yes, but if Voyager 2 were to encounter Sedna now, it wouldn't do a bit of good. It doesn't have nearly enough power to collect any useful data, let alone return it. Both Voyagers and Pioneers 10 and 11 have been essentially comatose for many years now: they're alive, but just barely.
Well, Voyagers 1 & 2 are still alive, albeit with some instruments shut down to conserve power. Here is this weeks activity report
r ts /index.htm
http://voyager.jpl.nasa.gov/mission/weekly-repo
If they did by chance encounter a large object like Sedna, useful science could be done. Things like the old Vidicon cameras onboard Voyager are not worth keeping on, since they are nowhere near anything that can be usefully filmed, they take a lot of power, are not good in low light, and I think need power to prevent them from freezing. I would guess the new Pluto missions would have much more efficient modern CCD cams, that could more readily be revived even after a long dormancy.
Pioneer 10/11 are now lost, they no longer respond to commands..
"You lied to me! There is a Swansea!"